As far as the affair, either it is happening or not. I am still committed to my marriage. If I give him the opportunity to confess I believe it would make healing easier than if he were caught or forced to confess.
Affairs are highly addictive. If he IS having one, he's NOT going to give it up voluntarily.
Ever see an alcoholic give up booze voluntarily? A gambling addict give up the slots? Not without hitting bottom.