One comment for HRH if he ever does read this, or for anyone else contemplating doing the same thing:
Sounds like you are in a pretty desprate, dramatic, and emotional situation. You must be twisted up. In situations like that it's natural to reach out and latch onto people to try and get them to validate you ("I forgive you") or help you or whatever. You're likley looking for an emotional connection you feel you're missing in your life, and this big dramatic scene is designed to create it.
Well, that's probably a mistake.
Perhaps you need to quit this because YOU aren't as emotionally available in your marriage as you should be, because YOU aren't as committed as you should be, because YOU aren't being the sort of husband you'd like to be, or something similar. The word here is YOU.
This is YOUR problem, not your wife's problem. I would strongly advise anyoen else contemplating this to carry their own water. By all means do what you need to do: Quit, get counselling, etc., but you don't need to dump this on your wife. You cheated on her when you saw SP's and you can't really undo that by confessing it all to her now. You probably should just deal with this on your own. All you're doing at this point is hurting her in an effort to get her to validate you. That's selfish.
Too late now for you, but perhaps not for someone else reading this thread.