How should I help her?

My bestfriend recently got married and it seemed like the perfect picture...but about a week ago I visited their house, and he litterally started beating her infront of me! She was standing in the kitchen and happened to say something about something he had said in the past, he started to get really angry and threw her across the room to the wall. I ended up jumping on him and I pushed him into a door with glass windowpanes. She is now no longer "allowed" to speak to me, so we met in secret. I don't know how but he found out about it and came around to my apartment. He stopped me on the stairwell and threatened me. He told me to piss off and leave her alone. Does he think because I'm female I'm going to back down? I've spoken about this to her, but she says that its her "fault" and that he's really very "sweet" but she provokes him. How the hell can I help her? Shes destroying herself and I am losing her...

,Sorry,if she's prepared to put up with this sort of treatment,there's nothing you can do.Seems like the battered wife syndrome.You can't help her,if she's not willing to defend herself,from this big man