It's hard to believe, but you know, for me it would be harder to believe "your situation" if there WASN'T an affair. You yourself said it - it didn't make sense the way things went. Well this makes more sense, to me. That may sound harsh to you, but it feels right to me. There had to be something else. This is what it was.
No use confronting your wife or discussing it now. It IS sickerning, and you would never want to do that to someone you loved. YOU would never do that in your marriage. But she's not you. This latest revelation does not change YOU. You are still who you are, regardless of the extent of the deceit and dishonesty.
You ever wanna talk, come and find me on FB. I think the advice you got is right - You need to step back a bit from the whole thing. Don't spend too much time on DB. Find something to take your mind off things.