Hello

I knew my best friend for 2 years before dating them, we were in a relationship for 3 years after that. I've known her for 5.
She's an incredibly damaged person and no matter the horrible things shes said to me and the way shes treated me, I can't let go.
She always convinces me that I'm in the wrong, that I was overreacting or that I should give her a break because shes going through alot. (She is in an abusive, messy family situation.)
I always feel bad and feel like I need to be nice and forgiving to her because of this.

We're not dating anymore, we broke up in December where she blamed me for the entirety of our relationship failing. She never apologized for that and we're still 'best friends.'
We shared alot together, I drew and wrote with her and those are my two favourite hobbies. We still do.

But she's a horrible person, everytime I talk to her about my problems I end up crying and getting into a fight with her. The fight resolves itself by both of us saying we're sorry and then it happens again.

I can't seem to let go of her because shes my best friend, shes been there for me through so much but it doesn't change the pain I deal with.
I've tried many times to break it off, so many people call her abusive and I know that, I know shes not good for me.

I feel like if I break off my friendship with her, the stories we had together would be a waste, I wouldn't have a best friend anymore.

I just need help, trying to break it off, I want to but at the same time I'm stuck.