Before I even finished reading I was thinking that she is probably cheating on you and is now aggressively projecting. ..Then you mentioned that she has cheated before.

I'd suggest you evaluate whether you actually want to be with her and if you can trust HER or not. Personally, I'd break up with her.

I could never be with someone who has cheated on me before. That is such a vile breach of trust and shows they how much they actually care for you. I would never be able to trust them ever again.

I don't want to say that people can't change because they can, but when it comes to cheating on someone, if you were disgusting enough to do it before, there's a good chance that you'll do it again.

Once a cheater always a cheater imo.