I can only say this is an ugly situation. Your girlfriend in enabling her roommate. The roommate has to take no responsibility for her behavior as long as your girlfriend continues to make excuses for her and allow her to be abusive towards her. The roommate has no incentive to change. Secondly, it sounds like your girlfriend cannot set boundaries, with the enabling of her roommate she sounds very co-dependent, which in and of itself is its own pathology. And last, but certainly not least, your girlfriend may be in physical danger should her roommate suffer an acute psychotic break.
You putting up with a triangulated relationship also says something about you. Do you care about this woman or feel sorry for her? If you care about her, you should be worried about her physical and emotional well being. Your relationship does not sound healthy for a variety of reasons which I have only touched the tip of the iceberg. I would encourage your girlfriend to get help. The roommate has likely been ill for a long time and she has to look at her own stuff and she has to decide if she wants help. I would suggest you think about the following, as long as the roommate continues to sabotoge this relationship, she doesn't have to look at any of her own behavior because she is too busy finding fault with everyone elses behavior. Good luck.
