PHENOMENAL advice you are getting here. There is not a whole lot I can add. I am much more of a "confront/expose" guy, as I believe the first thing one needs to have the "alcoholic" do is get the damned alcohol OUT of the house, but reasonable people come down on both sides of that argument.
I wanted to second what someone else said about the anti-depressants. They really help, and they do take awhile to kick in (2-3 weeks for me), so do that right away. There is NOTHING to be ashamed of there; you are doing what you need to do to be the best dad you can, considering what your wife has done to the family.
I found out this past summer that my 47 year old wife was having an affair with her 29 year old personal trainer. I know how you're feeling, it's like someone took a chainsaw to the middle of your chest, cut your heart out, and threw it on the floor and stomped on it. When I personally witnessed my wife meeting the OM in a parking lot, getting into his truck, and driving off, I had a panic attack and couldn't even drive. IT SUCKS.
But it DOES get better. If you do decide to confront & expose, Harley and Glass have both written good books on this. "Surviving Infidelity" is great.
