Definatley tell him about it. Yes it might be embarassing, but he is used to dealing with tough situations and he will act accordingly. I agree that a relationship that is built on trust must have honesty. You are going to keep that in the back of the mind for a LONG time, if you dont bring it up. and you are going to just hurt inside by not talking about it. It is going to come out sooner or later, either when you can't hold it in any longer, or now, so you might as well voluntarily talk about it. I know its tough. but i really think that it may have been an honest mistake. T will feel bad about it. and maybe the way he deals with it will actually help strengthen you guys' relationship.