You're too young to be dealing with this kind of drama. I remember how strongly I felt about people and things when I was 19 years old, but now I see that it was really the intense infatuations of youth. You should embrace these passionate feelings, it's the great part of being young, but you need to be a little bit more selective than this. I don't doubt that this woman may be (or end up being) a wonderful person, but it sounds like her life is very off course at the moment, and as objective observers, I think everyone is agreeing on the folly of continuing a relationship with her, particularly while she is still involved or living with someone else. And, lastly, I wouldn't be too quick to dismiss this guy's threats if he is as much of a screw-up as your implying. If you stick with her, proceed with great caution.