Is it normal to think it was my fault?

I've been best friends with this girl for a few years now but everything turned sour. See, I met her in high school and we were so compatible it was crazy. She was funny, cool and smart and we just went along so well...for the first year. She was the kind of person who made you into a joke but it was funny enough to laugh at..but you know it hurt. She's extremely passive-aggressive about issues and is a huge hypocrite. She'd go around telling people how much she hates people talking behind other peoples backs and then she does it more than anyone you'd know. She's taken my friends by hanging out with them more (they live closer together) and now they barely talk to me. Anyways, I grew to dislike her as soon as I got a boyfriend and I found out she's been flirting with him behind my back. I was stupid and thought if I spent more time with my boyfriend she wouldn't take him the same way she took my friends. Eventually I told her I disliked her but mentioned I wouldn't mind starting over with her but all she heard was I pretended to be her friend. She began telling people about the things I said to her but she twisted the words. She's now convincing people to hate me and I believed she said something to my boyfriend that made us break up. I've lost 2 best friends in the progress of all this and I can't help but I feel like its still my fault that it all happened. She's excluded me out of the friend group I was in (because she's the neutral person in the group) and told people the group was happier now that I was gone. I've apologized about what happened but she still believes that I was a bad person.