Trippin is right on the money. I'm so sorry this is happening to you I really hurt for you! What he's doing is not right. Setting him up wasn't exactly the right thing to do, but I guess at least you found out some truth to what he was doing. The right man for you would be patient with your inexperience and shouldn't be pulling away from you and seeking intimacy from anyone other than his wife.

You need to get into couples/marriage counseling or therapy IMMEDIATELY and sort this out, and find out what led him to this place of deceit. If he refuses to go, don't make plans to divorce or leave him just yet, but go to a therapist yourself to try and deal, in a healthy manner, with the affects this is having on you, so you can be better prepared with what may happen and how you will deal with it when it comes.

Maybe he has some sexual desires/issues, intimacy issues, a really strong libido... maybe he enjoys the thrill of a potential rendezvous, who the hell knows. But if you want to save your marriage and eventually find some closure to these problems, forgiveness, or, in the worst case scenario, the relationship, you need to get a professional involved.

Good luck! I'm happy you found love but I'm sorry this guy feels he can do this to you. You deserve better! Hang in there.