Helping a friend

I have a friend, she's more like my sister really. She's in a very bad relationship and she is taking steps to get out of it. It's been very hard for her though, she has a child with this man and her car and house is in his name, so if she tries to leave without his consent he threatens to call the police and claim the car is stolen. Anyways that's just a small example of the intense controlling relationship she's in. She is looking for apartments but can't afford rent without a roommate, and asked me to move in with her. I'm 21 and currently live at home with my parents. I've talked to them about it and don't think it's a very good idea, but I know if I don't help my friend I'll blame myself if something happens to her and I could have helped. Any suggestions?