I’m so sorry about what happened to both of you. I can only say your ex does sound very insecure and distrustful, and it’s understandable that her constant questioning and false assumptions about your feelings/motives in the relationship would make you walk away. Love requires trust, mutual respect and friendship, among other things.
It sounds like she’s had a rough time before, but she needs to recognise her own behaviour is just going to drive other people away and work on herself if she wants to have a better chance at a healthy relationship in future. Or, just stay single if it’s too stressful for her (not denigrating that choice at all. I’m single for precisely that reason myself).