BPD and Abuse

Good Morning! I have been friends with someone who was in a relationship with a BPD partner. Two years ago, he broke up with her but cannot get her to leave his house. She knows of me but her reactions to what he does that she doesn't control leaves him exhausted and feeling powerless. She will go into a rage and physically and mentally abuse him. She humiliates him on facebook and is now taunting me. Each rage seems to get worse but for whatever reason he is afraid to get the police involved. I see the facebook posts and others have confirmed this behavior of hers. He is not misleading and I'm not sure how to help him. After this last rage, I did not contact her or comment. I ignored it all. Does anyone have an idea of how I can help him? Tweet