I'm sorry but if he has lied continually about the affair, can you believe anything else he says. Beware, those that hide one thing usually hide others. I have done this myself, I'm ashamed to say. Hiding things from my husband was a game and he was an easy mark. I've since been through lots of counseling and am better but it is still my second nature to hide things such as one night stands, even though, I have fought hard against cheating when I'm manic I have a tendency toward cheating.

If this is a one time thing, with counseling you may be able to overcome the feeling of distrust. I would suggest couples counseling.