@decadence,
Block her on social media and your phone, and find someone new.
If you care at all about her well-being, there is every possibility that too much contact with you could equal abuse for her, either physically or emotionally or verbally.
Unless she is ready to leave (and she's not, because she's defending him to you), then get out of this situation before you find yourself on the business end of that guy's fist or his gun, or she does.