Honestly, just be there for her. She is really the only one who can change anything. If you force the issue, you could find yourself out a friend. I don't understand why girls stay with someone who beats them either, but I do know unless she wants it to end, and wants out, it's not going to stop. I lost my best friend a long time ago, because her man beat the crap out of her, several times, she would come to me all black and blue, a bloody nose a busted mouth...and I would "be there" for her, she would go on and on about how she wanted out, then when I did try to speak up for her and help her, by telling her we needed to call the police and she could stay with me she went back to him, and quit coming to see me, she quit calling me and told me to leave her alone it was her life...I was stunned, but nothing I could do about it. Good luck, hopefully she will open her eyes and get out.