What advice can you give in this situation ?

So, a close gf of mine is in a situation.She was suspecting her bf of possibly cheating. A few red flags was 1. He refused to add her to his my space account and 2. He made his profile private.She then went on to question a girl on his profile that had been out on a few dates with him prior to my friend and her bf getting together.Supposedly, he wasn't cheating. but upon discovering this, the bf went ballistic and called his gf (my close friend) ,a psychotic b****.Ironically, her b-day is in a few days and he said he still wants to take her out for her b-day. I advised her not to go, being that what he said was inexcusable, but she is still pondering it. Who is really in the wrong here and what would you do?