Why am I doubting my relationship?

I have been with my boyfriend for a little over 2 years. The whole relationship has made me feel like the happiest person alive. Up until last week I would get excited to see him. I couldn't stop smiling at him and the butterflies in my tummy kept coming. But last week I confessed to him that months prior I had had a small crush on a cowoker. The coworker was attractive to me and I use to be a very visual person. I found many people attractive but I had started to develop a little ceush on my coworker when he started talking to me more. I liked his outgoing attitude that my boyfriend does not have. I still loved my boyfriend and if the coworker ever tried to make a move on me I would have definately turned him down and stopped talking to him. I had done this on some occassions when friends (whom i found attractive as well but not crushing) would try to pass the friendzone. I would block them and immediately tell my boyfriend. So i knew that in this case with the coworker I would have done the same without a doubt in my mind. The crush on my coworker went away all on it's own. I hadn't stopped talking to him it just went away. A couple of mo ths later I quit that job and me and my boyfriend were talking about boundaries. My boyfriend told me that in to him if someone is to get feelings for another person then that is cheating. This gave me feelings of guilt and I let him know about the co worker. He got very upset but pushed it away and said that it was okay because me and him are still together and that it was months ago. But i wasn't able to keep feeling so much guilt and cried excessively for days going in and out of anxiety attacks. I told my friends about it who in turn told me that I cannot truly love my boyfriend if i had a crush on someone else. Now I keep asking myself if this really what love is? Do i not love him enough? I can't get these questions off my mind. I keep going to Google asking these questions and I can't stop freaking out. I wake up and immediately my heart starts punding hard. At night i can't go to sleep without calming down my anxiety. And during the night I wake up shivering from my anxiety attacks. Throughout the day i break down crying and shaking. And when I see my boyfriend we will be having a fun time and laughing and then I start bawling like crazy infeont of him. I tell him it's my anxiety and he tried to support me through it. I'm now really struggling with my thoughts. They come racing through my head for the past week. My have thoughts of breaking up with him but it just makes me panic and cry all the time. My chest hurts and I feel like throwing up. I cant concentrate at work and have no motivation to do anything at al. There have been moments where I feel a burst of warmth in my heart and I feel like there is clarity. I know that I love him and I know everything will be okay, and that everything I am going through is anxiety. I could be with him laying in his arms and think to myself that 'this is where I belong.' I also have visions of the future with him in it and I smile. Unfortunately they don't last long because of my thoughts.

I know I love him, he is an amazing person and we share so many laughs together. And like I said a week ago I was falling asleep with a smile on my face thinking of him thinking of how we met and imaging him hugging me feom behind sleeping together in peace. I would feel so in love just looking at him and would get butterflies every hug and kiss we shared. I just wish I knew how to get past this anxiety so I can give more to the relationship and be my happy with him again like before these thoughts even started.