How can I tell him.....

Just tell him next time he does that, that if that happens again he's history as far as a boyfriend is concerned. Be nice but direct. But it'd be nice if you assured him first that you really do like him, it's just that you don't like that behavior. If he refuses to listen you need to follow up on what you've been telling him. That may get the point across and maybe he'll really stop doing what been uncomfortable to you and actually start respecting you more. He absolutely has no business touching you where you don't wanna be touched. Don't put up with that much longer. He sounds too bold of a boyfriend for you because he's not respecting your standards and that's a very bad sign.

I'm sorry it didn't work out. But I'm glad you stuck up for yourself. Good luck!

Just be direct, honest, and leave no question that you only want to go so far. If that doesn't work, it's probably time to re-evaluate the relationship. Don't give ultimatums up front, but ask that he respect your wishes and that you really need him to do this for you.

If he persists, then tell him that you want some time apart, and stick to it. Judging by the age range, he's probably just feeling pressure from his friends, and wants to be like the "other guys", but most of those guys are just fibbing about their experiences.

just keep telling him to STOP
if he really keeps doing this to you, ditch him

Glad you moved on, and I wish you luck with finding someone better.

Make sure you are firmly telling him no. And don't say no, but then say nothing if he does it anyway. If he does that, physically pull away from him and tell him to stop and that you mean it. And yeah, like obscene said, if he keeps doing it, leave him.