Oh dude.. it's BAD. That just scratches the surface. Objectively, from what he has described, this girl is clearly manipulating him and he is beginning to believe it was HIS fault. My friend did nothing. She suspected he was cheating on her (he wasn't' and proved he wasn't) after kicking him out of her apartment (where he was living) on Christmas eve. My friend's mother also passed away 1 month prior to this.
This woman is a cold biitch. If I continued to describe the things she has said and done to him your head would explode with anger for him. I don't want to detract from OPs post though.