My best friend is a friend I graduated high school with in 06. We've been through a lot recently and she has always been there for me when I needed her the most. A few weeks ago she changed everything and was acting like a bitch to anything that moved. I met her boyfriend a while back and we really hit things off. Turned out we worked at the same place as servers (we started work 2 days apart from eachother so we went through the same stuff). It was three weeks ago when my friend went out of town and I still hung out with her boyfriend since we also were friends. We had a laps of judgement when intoxicated (I'm not blaming it all on this I take responsability for it) we slept together. I really wanted to tell her but how could I? So now for three weeks I have had that hanging over me cutting away at me. I figured it was not going any further for him but he's tried to sleep with other friends/ coworkers and he has made out/groped a friend when I was in the room. I found out from another friend that he has been fooling around with another coworker and last night he slept with her. I know it is none of my business but I don't want to stand by anymore. He says he wants to marry my friend but I think that is a load of bull. I don't know what to do. I don't want him getting her sick and I don't want her getting hurt. But how can I protect her with out losing her as a friend? I mean I was the other woman too. I'm unable to get much sleep anymore because of this. Please help me. I love my friend too much to see her hurt since her last boyfriend cheated too.