Should I leave?

I’m 24. I’ve been in my high school group since we graduated. I’ve always been the person to never be that close to anyone after years of rejection from family and friends. So much is has shaped a belief that everyone will reject me. Anyway within that group of 6 I got close to two others so we made a mini group of 3 let’s call them A and B. I genuinely thought these two were my closest friends and we even went on holiday last year all together. Because of my belief I don’t make plans which I know is something I need to fix especially thinking of these two as my closest friends. But fear of rejection plus these two being a lot more popular than me I couldn’t do it and guess I got comfortable not doing it. I showed up to everything. This year my priorities changed a bit I wanted to save for a house and I got a dog and my partner moved in with me. I was still seeing them but not as much because they were going to events I wasn’t interested in. But I made effort in other ways like driving them to an event I didn’t even go to. Me and A saw each other one on one a few times too and I said no 2 times to that for really valid reasons. That’s when I noticed a shift despite telling them multiple times I don’t have a messaging app they countinued to message there. They started not sending events in the group. I got sick so I had to cancel on something I was going to and no one checked in on me. And then I found out those two planned a whole holiday without me. Didn’t ask me at all. So I bought it up that I was feeling excluded. I felt I got responses that were quite dismissive listing all the reasons going on for them on why they weren’t showing up for me or very surface level apologies (sorry about that or sorry if you felt that way). When I expressed I just wanted some accountability it got flipped on me that I was attacking communication style and then B told me “we don’t do well one on one” basically saying we were never close friends and the group of three was because we were both close to A but not each other. So of course we are no longer friends. A took the accountablility made a genuine apology and set action. And I did too to make more effort. But since then I still feel really excluded by A. I’m making an effort but it’s like a walk or lunch. And maybe every second week and there’s kinda an elephant in the room that’s not being addressed. While with B they are going to cool events or out. I just think we have reached the stage where A is closer to B and I’m hurt and jealous by that especially with Bs actions towards me. And the bigger group I tried to make plans and they didn’t go ahead because no one followed up with me. Should I just leave the situation entirely? and the reason I’m having so much difficulty with this is if I do I have no friends. Like surface level at work but no one I would go out with and see.