Don't do anything but take care of yourself for a while...you can't do anything but that right now.
You can go to counseling, but more importantly your wife needs to go to counseling, she's the one who cheated.
Read from the healing library here.
Post about what you are going through. It helps. I found this place nearly 2 years into my ordeal. There is nothing more terrible on this side of Hell, and if I had to describe Hell, it would be a place where you love someone and they betray you like this and it never ends.
I remember that first night after the confession, the days stretching out into months, the pain in the gut, the nights without sleep (I didn't sleep much for days). I found out 9 years after the fact. I'd been close to divorcing my wife because of our relationship problems, all stemming from this affair and her major underlying psychological issues which she had hidden.
Remember a few things.
You do not know the full story.
Almost all WS's lie their ass off about their affairs after being discovered or confessing.
Almost all WS's have major FOO issues (family of origin issues) that they haven't disclosed or that you know about but don't understand their impact on the person psychologically.
Your work is just beginning, to understand, to heal, to come to the point where you thrive.
YOU DO NOT HAVE TO MAKE ANY DECISIONS RIGHT NOW, NO MATTER WHAT ANYONE ELSE SAYS OR DOES.
You do not have to reconcile.
You do not have to stay married.
You do not have to forgive...although it is better if you do eventually. Forgiveness does not mean reconciliation, it does not mean that you stay married.
Do not forgive to quickly.
Do not mistake sadness and regret for true remorse, TRUE REMORSE is something else altogether different and you will know it when you see it.
You will never, ever, forget this. This is one of the cruelest things you can do to another human being, it is abuse, it is sex abuse if unprotected sex is involved (and it almost always involves unprotected sex although WS's will deny this to high heaven till they finally confess), it is psychological abuse.
I received an e-mail from his wife. It was devastating.
At least you know. Now, find out all you can from her, how she knows, what she knows, when she knows, and everything else you can think of or she can think of, and do not share this information with your WS. Let her tell her story, and find out what makes sense. Usually there are so many lies, so much TT (trickle truth), so much gaslighting, that both BS's struggle to find their footing, and the WS's can often concoct a lie together.
You have come to a good place.
Read "Honey they always affair down." http://www.survivinginfidelity.com/forums.asp?tid=326449
That posting line has more truth in it than you can believe, especially at first.
If you need to understand how really F'd up someone can be, while seeming to be all together on the surface, even in a long term marriage, you can read my profile.