Was Gaslit

I recently broke off my friendship with one of my really close friends (of like 2-3 years). Let's call him B. He used to be this really really nice guy who was awkward but super kind and caring. When we first met, he was genuine and full of life. About a year into our friendship, this other guy joined our friend group (let's call him A). I had known A for a while and was pretty good friends with him, but not as close as I was with B. However, I started to notice that my friends were hanging out with A a lot without me and that he was the one making plans. He seemed very interested in B. He told everyone that he was "not close" to me, despite the fact that he was closer to me than he was with most of my friend group, including B.
Fast forward a few months, A and B like each other and I am no longer friends with A cuz he clearly tried to kick me out of my own friend group to get close with B. B starts to treat me terribly, always inviting A to hang out with us even though I told him I'm not comfortable with A. I took B to a party HE wanted to go to and he disappeared for hours to hang out with A. B also lost that happiness and genuine attitude and began to say some awful things to me, like ask if I was going to start taking Ozempic. He stopped showing up for my performances or asking to hang out, unless A started to pull away from him and he was feeling extra lonely. One year later, I finally called it quits and told him that he wasn't being a good friend. I couldn't be his backup friend every time A treated him like shit. While I was trying to explain the things that had hurt me, he said he was sorry I was hurt but that he didn't think we were ever close or had connected. Funny, considering that's what A used to say about me...
Anyways, this all went down last week lol so I'm still figuring that out. IDK if this a common experience, but yeah really sucks and I can't believe he chose to gaslit his way out of taking accountability.