So I have these friends...

They're dating, and have been on and off for about 2 years. Recently he's not been letting her come and see her friends and they've become like hermits, he wont let her drink or smoke anymore unless he's with her watching every move she makes.
Recently I have been told that he's been hitting her and I have been told that he's hit her before and bruised her. And cause I was her best friend he's tried to hit me too, but I wouldn;t let him hurt me the way he does her. Even though he has reduced me to tears a couple of times. He has even pinned her by her neck to a wall cause she wanted to come and meet me for a chat. Now I never see her anymore and really would like to with out him being there cause I sometimes fear for her safety and stuff, he's vile and horrible but she wont see that cause she's so 'in love' with him.

Could anyone be able to give any advice on how I would be able to get the message through to her without her actually being beaten black and blue?

xDeex