AITAH for being close friends with my best friends ex?

as a child i was quiet and antisocial so making friends was sort of a challenge for me. My parents seeing that, decided to introduce me to their friends son. Now my dad has been friends with this guy for a good while. They spent their collage years together, saw each other get married, and just shit like that. Me and the child of this friend let’s just call him A got along pretty well. When we turned old enough to enter first grade we were supposed to go to the same school and be in the same class but my parents disliked the school so it ended up being a fail. Anyways, fast forward many years I end up making a new friend and she becomes my best friend. We’ll call her V. We were inseparable. Then this stupid guy friend of ours who is also friends with A decided to set A and V on a date and it wad a great idea then but gosh.. So they end up dating for quite a while I mean a good year or so and then V starts talking to other guys but never actually doing anything with them. That obviously pisses A off. Just to be clear the moment they started dating I immediately backed off of A and started being a bit more distant but obviously not entirely ending the friendship, more like a respectful friendship with a few boundaries that weren’t there before. I didn’t mind one bit though.

So V gets dared to hug or kiss this other guy (i cant remember correctly) for like 5 bucks and she does it and someone ended up taking a picture of the moment and sending it to A. They fight bla bla bla, and the. A does something so incredibly stupid. He leaks some other pictures of her.. Now they you couldn’t even tell my was her and they weren’t even that revealing. But of course it was too late for her to fight now. It affected her a lot and I was there for her every second of the healing process. I blocked A, made sure no one got close to her, i literally gave it my all for her.

What V does next hurt me a bit, she got back together with A. I could tell A was really sorry and he truly meant it when he said he’d changed. They did eventually end up breaking things off again but I obviously thought things were okay-ish. No more hatred. Then a few years later I move to another neighbourhood, start at a new school, and we drift away a little. We still considered each other best friends though. In my new class A was put in with me. I guess i wasn’t surprised. He told me all about the things they did and stuff like that and I couldn’t avoid him at dinners or when he and his family came over so I decided to forgive him.

After finding out she said it was totally cool but the second we would argue she’d bring the fact i was friends with her ex. She always blames me for it as if I was the one who made him do it. I’m quite tired of it because it’s not even about A anymore. I could drop him anytime. It’s the same thing over and over again. She just blames me for everything wrong in her life and I’m over it.