First of all, I'm sorry that you are going through this. It is no doubt painful and difficult.

You said that you don't think it's fair that you now have to spend the rest of your life with trust issues with the person that your supposed to trust with all your heart. You don't.

If you are having trust issues with your boyfriend now as a result of this, that is completely normal. If you still are having them ten years from now, that would not be. He was drinking, he was caught off guard, and it sounds like the moment he realized what he was doing he stopped immediately, left and admitted everything to you.

I hate blaming alcohol, because we make a choice to drink - but we make choices based on information. Up till now he didn't know that dancing and alcohol could lead to him being caught unaware and kissed. Now he does. What is he going to do with that info?

You've talked about settling and whether you're okay with it. There are a lot of jerks out there, that is true, but three years of an absolutely beautiful relationship thrown away over an alcohol induced accident that he ran from and then ran to you with a confession... you might be shooting a little high. This does not sound like a 'settle for' this sound like a bad mistake and one that he's sorry for.