I think I looking for someone to say I’m not being stupid for staying and things will get better
OP, sorry, but I'm not a vending machine. I don't have a slot where you can put a coin in and get exactly what you want out. I'm not a robot! If I knew you I would give you plenty of hugs, would be there to wave your flag with you, would try to find other ways to cheer you up, but I am not willing to look at a situation like this and go 'yeah, it will all be fine'.
Just because lots of people are telling you you'll get over this, or can get over it, doesn't mean you will. Framing this as just a kiss is also wrong. Your trust was broken and he showed himself to you in a different light. Yes, a few months in is different to a few years in, but the premise is the same - you don't kiss or do inappropriate things if you are in a monagomous relationship.
The fact that he did this means -
a) He had issue with you at the time or doubts but didn't want to tell you. He wasn't sure if to break up or not. Instead of telling you, he went out and put himself in a situation where he knew he's be tempted, tried something naughty to see how he felt, and went from there.
b) He wanted a taste of another woman regardless of any issues he had with you, and knows it's wrong
c) He cannot be trusted when he's drunk. Poor excuse though. Unless he was so wasted he accidentally mashed his face on hers as he got out of the taxi, I think he knew exactly what he was doing.
I think it's likely to be b), hence the 'deserve' comment.
Once trust is broken, it's very difficult to get back. Future doubts about his behaviour or will lead back to that night. If this wasn't an issue, you wouldn't still be thinking about it, and I think it's very likely that it will continue to gnaw away at you.
I believe that if he were to break up with you and meet someone else, he may well never cheat again, but if he says with you (the person who put up with this), then that often sets a precedent. Despite passionate claims otherwise, when you stay with a man after they've done something like this, they think less of you. They might be extremely grateful that you've stayed with them, they might thank theur lucky starts for the 2nd chance, but unfortunately, you've marked yourself out as someone who'll be put up with this sort of thing. It then suggests you'll put up with more than another type of woman who would have said 'fuckity-bye' the instant she found out.
You might think- 'But I DIDN'T just 'put up' with it! I was angry! I almost left him! We had a huge row! He groveled! He was very sorry! I'm very assertive too'.......yes, but unfortunately, what he sees is -
My Actions = Nice woman I like who's decided to stay with me.
Women often come on here years down the line and wonder 'why'? Why does my husband do things like this? Why does he keep doing that, after all the unhappiness and arguing?'
The reason, OP, is because their behaviour/actions works for them. In fact, it's worked so well that the woman has actually stayed, married him and had his babies! BINGO! A win for him!! It may feel or seem like the total opposite for the poor woman, but in the end that's the net benefit his behaviour has got him. Nice eh?
Some men will also be pleasant to be around, generous, supportive, they might be seen as a 'nice' person by everyone around them......yet they still cheat. That's because in their case, cheating is something outside of their relationship with you. That is, they don't cgeat because they're unhappy with you. They cheat because they're unhappy with themselves. They want a bit of naughty thrill whilst still remaining in a relationship with a dutiful, lovely (loyal) partner. They want the ego trip, they want a boost to their self-esteem, they want to feel virile and desired by other women except for you. It's not an excuse, but it's a liability if he's like that.
I sincerely hope that I'm wrong, but I'm hoping this will be food for thought for you.