Easy.. Don't. It's none of your business so just stay out of it and let nature take its course.
You should tell your friend that he is cheating its best that she knows.
You tell the truth and accept the consequences.
You would not like it if your best friend cheated on you with your boyfriend so that is not a nice thing to do to your best friend. First, you should stop saying you are best friends with the girl when you are 'cheating" with her boyfriend. Best friends do not do that. Second, you should stop going out with her boyfriend. Third, you should tell the girl that the guy is cheating on her, even though you will need to tell her that it is with you. If he does it with you, there is a real good chance that he would cheat on her with someone else. Finally, both of you should dump the guy.
Ask them!!! And if you are wondering they probably are.
Tell him to come clean about it, or you will. Give him some time to do it himself, but if you don't hear anything about it then you should tell her yourself.
Well think of it this way: Who is more important to you? Your best friend or your boyfriend's friends?
talk to her tell her how you feel
If I was in your place, first I would approach the boyfriend and tell him what I know. This gives him a chance to do the standup thing and confess. If he doesn't then I would try to get some proof to show her when I break it to her.
Tell him the truth, say you like girls.
You should tell the other girl and both break up with your boyfriend.
Tell your friend that her boyfriend wants to ask you out and she will think that hes cheating on her with you. Next she will breakup with him when she does he will settle for you
YESSSSSSSSSSSSSSSSSSS