It was a year ago, you were drunk, you need to move on.

Man is falliable we slip we stumble yes forget it and move on. Drink is slow poison. Mind you I am in no hurry.

That IS icky and very unfortunate!!
I can see why you think you may very well be doing the right thing, but it is still nothing I would choose to do.
Even knowing that it might make things worse, I'm afraid I would feel compelled to 'fess up'.
Secrets are not something that I would want to be a part of my relationship with someone I love.
If the situation were reversed, I would rather know the 'horrible truth', must as it would break my heart.
It feels like a matter of respect to me, and I have the utmost respect for the man whom I love. If I fell down in showing him respect, by kissing someone else, I would feel like it should be up to him to decide whether or not it 'meant anything'.

If this had just happened I would say fess up but you said it was a year ago. Has it just been the one time? If so, I think its too late to say anything but I would remember how it makes you feel so as not to do it again.

I agree with sb116. Forgive yourself, and don't EVER do it again. Be careful how much you drink in mixed company, especially if you are not accompanied by your boyfriend. Being drunk, as you know, takes away your reasoning, and your inhibitions. But I think the time has passed to tell him.

It was only a kiss
and your only human
dont worry about it
put it behind you and move on
have you learnt anything from this? if the answer is yes then your guilt has served a purpose,, forget about it and move on

p.s honesty is not always the best policy so dont tell him, theres no need, it will only make him worry and wonder ?? if maybe more happened? so no need to hurt him for no reason

if he kissed an old girlfriend would you want to know about it?

this is such a touchy, touchy topic...and i live in the inbetween. first i think that the compelling feeling to tell on yourself is guilt and to lay that on your partner today, a full year later, would simple be selfish. you'd unload on to him. you crossed a bound and if it meant nothing and it is sincerely never happening again with anyone, keep your mistake and burden to yourself. BUT the other side of the fence is that if this is a part of your character he deserves to know.
if this were me, i'd be asking myself why this happened (does lean on the drink; there still had to be a motivation of some sort whether it makes sense or not) and then make my decision.