Should I keep searching for the truth, or let it go so we can try to work through this?

I wouldn't bother to go behind his back for anything. If you need to do that, you know what the answer is. I would stop all accusations now and go straight to a counselor. If he won't go, go for your own peace of mind. Only you can decide if you are willing to stick this out. I don't know your history with him. Personally, I would say that if the trust is broken, it is very difficult to fix and I would walk away, but I also know that marriages can survive this. The bottom line is do you both want this to work? If so, you both need to sit down together when there isn't drama and high emotions and talk about what you both expect. Be firm. Tell him that you deserve and expect honesty and trust and nothing less. But if the conversation becomes drama oriented, then no one will win. Talk as if you are first getting to know him and put accusations aside. Listen to what he says. Don't let him sweet talk you, but don't be overly suspicious either. If you really listen, you'll get your answer on whether he is a decent guy who wants to try or just a schmuck. Good luck! I hope it all works out!