How do I move forward?

Hello, I am new to this forum, and would like to preface this story with the fact that, on top of the diagnoses mentioned below, I also have been diagnosed with Bipolar, C-PTSD, and OCD. Pretty sure the other person involved in this has or had BPD. Now, on with the issue:

A couple of years ago, I started at a new job, and befriended a few people (2 females, and one male, and I am a female) that I worked with. I’d just gone through a tough time financially and emotionally, and didn’t have any friends, so I suggested that we all went for coffee. I ended up having a one-month psychiatric stay due to burnout, and when I was there, the male friend asked me when we would meet up for coffee. I said after I got out of the hospital. When I got back to work, one of the female friends had quit, and instead of hiring a new person, the boss overburdened me with extra shifts. The other female friend in this dynamic couldn’t meet up, so I ended up just meeting up with the male.

I am in a long-term relationship, and wouldn’t normally meet up with another guy, but for reasons, I thought this guy was safe, because he didn’t seem straight (I found out later I was wrong, but I guess I shouldn’t have made that assumption). Anyway, my partner knew about the friendship and each time we were meeting up, and seemed fine with it.

We spent a lot of time together at work, with usually just us two working together due to having a small team. He’d even come to visit me on his nights off, and hang out with me at work for a few hours. We hung out outside of work a total of 6 times within the space of a few months (always alone), and we messaged each other more-or-less every day over those months, sometimes multiple times, nothing suss, just memes, TikTok videos, general chit-chat, pictures updating each other about our day, etc. The thing is, he was the one adding me across all the social medias, or suggesting that we connect. And he was always messaging me first. We both had mental health issues, so we also talked to one another about those things, sometimes at work. He stopped paying attention to his job, and was underperforming.

He was a person that gave people compliments, but seemed to give extra to me. He would tell me that I looked “bangin’”, that my hair was “luscious”, or say that I smelled nice, that I was kind, intelligent, had a “beautiful soul”, and that I was pretty. I became emotionally attached, because we were spending so much time together, and because I felt he understood me, I also told him things that I had only told my therapist or my partner up to that point. Whenever we went out, he mostly picked me up, and we’d have so much fun together that we’d lose track of the time, and I felt as if I was neglecting my other responsibilities. He made me feel alive again after such a difficult period in my life, and I felt myself drifting away from my partner.

He told all his friends about me, and his mum came in to a to our work just to spy on me, it felt like. He met my parents too, and they gave him their old records to sell or keep (which cost a mint and which I never got back).

I was waking up to 6-8 unanswered messages from him, but sometimes when I’d respond, it’d take him a while to reply. These texts from him would often be sent after midnight. He’s message me inside jokes randomly during the day. He even started saying “us”, and snapping me whilst he was at work and I wasn’t, sending videos of him bored at work, etc. It was all a bit overwhelming. We did a few things that I haven’t done in many years, like jumping into cold water in the middle of winter after we went on a hike, getting high together, and just emotionally opening up to someone. It felt good to be validated, and I felt we shared a lot of mutual interests and commonalities, like movies, music, art, interest topics, all of which we talked about in depth. There were some red flags, like when he would sometimes cancel hanging out at the last minute, but that was mostly due to someone being sick at work and having to take their shift, or saying that he always hurts the people he cares about (I thought this was low self-esteem talking), and went the topics went to dating and relationships, or crude jokes. He even asked me if I liked my partner, to which I replied “yes.” And he admitted that the first time they worked with me, they were nervous, but in a good way, because they didn’t want to mess up.

They even said they liked me and would never abandon me or ghost me. We never kissed or anything like that, we hugged a few times in a friendly way, but we really bonded emotionally. I genuinely wanted to help him with his issues, and I felt he wanted to help me with mine. It’s hard to explain, but I really started to like them, and one day at work, I broke down and told them, but then said if was ridiculous, because I was already in a committed relationship. They replied that it wasn’t ridiculous, and then I re-iterated it was, and that I couldn’t start anything with them, nor leave my partner. They knew I was in a relationship when they started the friendship with me. When I then asked how they felt, they said they felt nothing and promptly left the room. They then gave me a bunch of jumbled excuses the rest of their shift and hung around after they had finished, but I told them to go. Their reaction devastated me, and they made me feel crazy and delusional, as if I had just imagined all of their advances.

A couple of days later, I got a long text, basically saying that they “definitely” didn’t feel “that way”, and that we should find a way so we didn’t have to work together anymore, and that they didn’t want to add to my guilt. I was trying to save the friendship, and had to go in to hand in the work key, and went I saw them, they told me to disregard the message they sent and that we could continue being friends. I regretted what I had confessed, and so was grateful for this, as I really thought I could do this. At the time, he was my only friend, and I didn’t want to lose that. I ended up confessing to my partner how I felt. He was upset, but glad I had rejected this guy. We wanted to work on having better communication moving forward.

I worked with this guy a couple of times afterward and apologised for my behaviour, but he made a throwaway comment like “well, you rejected me”, which made things awkward. Even though I was heartbroken in a way , I thought I had made the right choice, and that we could be friends moving forward. So I was friendly, nothing more. I chatted as usual, kept things light. But he decided to give me my books back that I had lent him, and also talked about his emotional issues, which I tried to help him with. I then was off work for a few weeks due to minor surgery, and came in a few times, once to buy a present, and another to meet the new colleague my boss had finally hired. Each time, he was never alone, and I chatted to him, because I thought we were still on friendly terms. The last time I went in, it was to confront him about unadding me only on Instagram, which he said was an accident, but I don’t believe. He had been looking at all my Snapchat stories beforehand, and turned his location off. I had sent a few sporadic funny videos, but nothing too much.

The only thing he responded to was when I received my Autism/ADHD diagnosis. It had been a long time coming, and it was one of the reasons I found his contradictory behaviours so troubling and hard to read. He responded empathically to this news. It’s also why I was grateful that he still wanted to remain things in spite of everything, as it is rare for me to be able to establish deep friendships. I had also told him that I had told my partner what had happened, which I probably shouldn’t have done.

A few days before I was due to start work again, I received another text message saying how uncomfortable it makes him to see me, the fact that he thought we could have been friends with some space and boundaries, but that he felt like he hadn’t gotten that at all. He then blamed me for his panic attacks, and finished with what felt like a thinly veiled threat that he didn’t want to cause any hurt, but that he had to think about himself “as he hadn’t at all in this situation”.

He wasnt at work when I got back, and so I felt I had to let the boss know what had happened, but he went one better and decided to complain about me to HR, just because he didn’t want to work with me anymore, telling them a few lies in the hope I’d get fired. In the end, all they could do was give me a warning for giving mental health advice to a colleague, whereas he was given a warning for harassment, and inappropriate comments after I told my side of the story. I was told I caused a lot of hurt (which confused me, as it was the other way around), and when I asked if I could apologise, I was refused the opportunity. We didn’t work together after that, and a month later, I found a new job and blocked them everywhere.

The experience ruined me making friends for me for quite a while, and gave me trust issues, as they made me feel guilty and shameful, and like I was a bad person, just because I had developed feelings I wasn’t willing to act upon, and they denied their’s, for whatever reason, to save face, maybe. I was just trying to do the right thing, please everyone, and ended up pleasing no-one. The fact that it happened at the time of my diagnosis also just solidified my feelings of social failure. I had a weak moment where I thought I was being over dramatic and I unblocked (but didn’t and had no intentions to contact) them, to which they promptly blocked me everywhere, except one platform, which they waited a few months and blocked me on there too. We weren’t even following each other anymore. And I checked because I was confused how it ended, and trauma-bonded.

I have been in intensive therapy for the past year or so over this (as well as other traumas I have experienced) and am working hard to move on with my life, and build a good future with my partner, but I still have nightmares and insomnia about the experience, have a panic attack when I see someone who even mildly resembles him or his car, and cry over it more than I should. It’s time-consuming, I feel like they stole a part of myself, of what I thought about myself, that I can’t get back. I also don’t think it’s appropriate to tell my partner about this pain, and I find it hard rehashing it again and again with my therapist, as I am embarrassed I haven’t made sufficient progress. I have had other traumas in my life, some probably more objectively significant than this, but this incident is what is at the forefront of most of my distress, with the other factors taking background roles. Sometimes I think I’ll never get over it, and it fills me with despair and frustration.

I don’t know what the point was, how they really felt, I question myself, and am full of self-loathing over my mistakes. Sometimes, I have good days, but most of the time, despite actively making healthy changes, working toward my goals, and keeping busy, I just feel this deep pain in my heart. I cry before I can stop myself. How do I let it go, forgive myself, make the pain disappear, and move on from this experience?

Tl; dr: I lost a friend cruelly, and it has scarred me, how do I move on?