I agree with everyone here. Dump him. If he wants to live with her, then she can take care of him. I was going to say that when I read the title of the forum, and after reading your contents it's pretty clear that he's not somebody you want to have a committed relationship with. While I normally try to avoid taking sides when I only have one person's part of the story, this one is fairly clear-cut.

You can do better than him. Find somebody that takes the relationship as seriously as you do.