So my boyfriend's cheating.?

All you gotta say is how you really feel. just release all your anger in the most ature way possible. if i were you i would say: You are the most immature man i have ever met. What did you see in her and not in me. If you are gonna go and cheat on other people you should at least have the balls to tell you GF that i dont like you anymore. i hope you feel like shitt. :)

Sorry to say, but it doesn't matter what you say to this guy, his behavior isn't going to magically change because you don't like it.

I'd just end it, say i'm moving on, byebye! Seriously, if he didn't care about how he behaved while he was behaving badly, he's not going to care about it now.

Yes, he might whine and moan and say he's sorry and make excuses for his behavior, but he's going to turn right back around and treat someone else like crap.

Just move on and forget it.

Cheaters never "truly" feel bad for what they do, no matter what you think you can do.

Just tell him since he's not ready for a commitment, you are moving on to find someone who is.