IMO your first mistake was in telling him! As you say, it was a drunken kiss, and you had only been seeing each other for 3 months. Yes, he has overreacted, but I'll bet that he was drunk, and all the hurt was inside fizzing away, ready to burst out at the right (wrong!) time. I personally would rather not know if my dh ever did anything like that, because a kiss means so little in the grand scheme of things.
Of course you can deal with this. Your dp is just hurt. You thought that both of you had dealt with it, but he obviously hadn't. My dh has said some HORRIBLE things during the course of arguments, and so have I come to think of it. You just have to remember that you hurt him, and he now wants to hurt you - simple! I'm SURE that he doesn't actually think the you are any of the things that he called you, otherwise he would not have stayed.
This is just my opinion, but I would do the following:
Tell him that you love him (if you do)
Don't apologise for the past incident. Just say that he knows that you regret it, and that you apologised for it at the time. (IMO You shouldn't have to spend the rest of your life apologising for it, but don't say that bit!)
Move back into the bedroom. You probably compounded the hurt that he was feeling by rejecting him in this way, and this could be stopping him apologising for his comments.
He probably doesn't trust you 100%, and trust, once lost, is impossible to regain. However, he will have to learn to live with that if he wants to be with you.
Speak to him. Stay calm, and don't take offence at anything he says. Just remember that he is trying to get the upper hand in his own eyes, because you have made him feel bad about himself, and probably insecure. Good luck. You have done nothing BAD, just something that probably 50% of us have done at one time or another, or have wanted to do when drunk!