AITAH for slowly cutting ties with my closest friend because of her toxic manipulative cheating ex

I’ve been friends with her for years, and honestly at first I understood why she keeps forgiving her ex even though he cheated multiple times. I’ve been there before too, so my approach is really just to be there for her every time she has problems in her relationship. I still remember the last time they broke up, we were constantly talking, checking in on each other, and just hurting together over everything.

Of course, I still talk to her like a normal friend—the type who says “don’t go back to him” even though you know she probably will anyway. I don’t want to go into too much detail, but aside from her ex being a cheater, we’ve also heard things he says to other people. Like he says no one else would want my friend because they’ve been together for so long, which honestly sounds really bad. The way he says things feels like there’s no respect or admiration for her.

Also, he used to hang out with us and somehow became part of our circle. But the pattern is, every time he does something wrong to my friend, he ends up distancing himself from us too. Then when they’re okay again, he comes back like nothing happened.

We’ve also tried before to welcome him again for her sake. Like we set aside our feelings and tried to be civil with him, but after all that, he just cheated again. The audacity, honestly. That’s why now we can’t bring ourselves to fake it or welcome him again.

I’ve also noticed that she’s become distant from us, probably because she knows her boyfriend isn’t welcome in our circle. And honestly, I don’t want to force anything.
I’m not saying we won’t be friends forever, but I do feel like I’m slowly letting the friendship slip away. It’s just sad to think that at this point, we might even end up becoming strangers.

AITAH for that?