Also, be careful for yourself. He's probably reading her e-mails and is regarding you as an enemy.
I had a friend with this problem, let's call her Anne. Anne's friend was in an abusive relationship
and was venting and asking for emotional support. Anne listens and is supportive, and when Anne's friend finally leaves the abuser... the abuser starts cyber-stalking Anne. He had read their emails and gotten her IP and somehow managed to get personal information about her. He would basically find her online and start making death threats. This was years ago, and Anne is fine now, but it's scarey, scarey stuff. So PLEASE, be careful. It sounds like your friend needs help, but it's hard to say what kind of situation you may accidentally find yourself in.