How to tell my boyfriend I cheated on him?

how can I tell my boyfriend that I slept with his bestfriend(which is a girl)?

Some guys are really turned on by girl on girl action. He may not care...? If you are going to do anything... dont lie. If you were able to cheat on him, your feelings for him may not be as strong as you may have hoped. If he really cares about you, he should forgive you. And if he cant, then you learned something about him. I would sit down and talk to him in person. On the phone runs the risk of him hanging up on you. Just remember that you would want the full and total truth if he had cheated on you. Also, be respectful and take the blame for it. If you really do care about him, make sure you tell him that. If you dont plan on doing it again, its also good to assure him that. Give him some security... I think his biggest problem will be the insecurity you created by cheating on him. Goodluck and be honest.

well...I kinda disagree...im the type of person who does this...
if a guy cheated on me, and I find out or he tells me...then its over, you should know better and think before you make a action that you might regret...so its likely that he may dump u.
but, yes I do agree that you should tell him that you cheated on him...and not with a guy, a girl...and see what he says...and if he forgives u, then congratz, but in a way...he might be thinking something in his mind like a 3 sum...