First, I'm really sorry to hear you're going through this. Second, are these things that these two have done been told to you by her or proven objective fact? The triangulation here is strong. Deliberately pitting you up against people who are (giving the benefit of the doubt) abusive and dangers to her life is a pretty messed up tactic. It sounds like you have this feeling of rescuing her, protecting her from these people.

As awful, as blunt, and borderline cruel as it may sound. She is an adult, and she is making choices right now that hurt you. That is an extremely emotionally and mentally tortuous thing she is subjecting you to. If what she says is true, she's actively choosing those scumbags, or threatening to, over you. That's a huge sign something is amiss. If she's lying, whose to say what she's saying to these people about you? Also, would you want to be involved with someone that morally bankrupt to lie about something like that? Or going back to the previous point, disordered and disturbed enough to threaten going back to such people saying they're better than you?

I know it's hard, but this situation is both toxic and ultimately dangerous for you. I know it's hard when you love somebody. But at a certain point, no matter how fucked up the situation. You have to protect yourself.