I regret what i did today when i got tipsy...?

like i got out of work today early and hanged w some friends. we decided to go drink and smoke under this bridge, i don't like smoking but i do drink. and so i got tipsy. then only this guy and i were left in the same spot and kept talking about random stuff while the others went a little far to sit down and talk to there's who just had came. and so the guy that i was talking with was hot, and so we just started dancing to random music on his iPod. i was having a good time, but then we made out. i was thinking that his green eyes, red lips and pale skin and didn't care about nothing else. after making out we just ignored each other because we knew that we don't really like each other like that. anyways the worst part is i have a bf... and i just feel so guilty, he knows i drank but don't know what I did.. i don't know what to do with this guilt in me.. should i tell him? should i break up w him and don't ever tell him? or tell him and see what happens? help please! :(