RAL, Read and reread Divorce Remedy (sounds like you have already started that). If you can afford it, sessions with a Divorce Busting coach will be some of the best money you have ever spent (go for the multiple-session package if possible). I struggled to come up with the funds for my sessions, but I'm very glad I did--my DB coach always made me feel much stronger and more hopeful and more confident about what I should do. Even though my H moved out a month ago, he was still living at home for over a year past the bomb, and I don't think he would have been around for nearly as long if I hadn't been DBing like crazy, and even when he moved out, he was clearly indicating that he wasn't at all sure it was the right thing to do, but he felt like he had to do *something* to get unstuck, and that was all he could come up with (naturally, dumping his mistress wasn't an option he favored).
It will seem unbelievably difficult, but the best thing you can do is to take your focus off of your W, and put it squarely on yourself and your kid(s). Make changes that YOU think you need to make--things that you intend to keep up for the rest of your life, regardless of what happens in your M. GAL is very, very important. So is acting as happy as you can possibly manage, especially in front of your W. It takes a long time, but "fake it 'til you make it" does work eventually. We all know how incredibly hard this is, but if we can do it, you can too.
Find healthy ways to deal with your stress (away from your W). Exercise, call a trusted friend (very important to choose carefully who you talk to about this in RL, as most people will not understand or support your DB approach and you will have to defend your actions instead of getting support), journal, get in your car and go someplace isolated and do some primal scream therapy, hit a punching bag, practice martial arts or yoga...whatever works for you that isn't harmful to anyone or anything animate.
Finally, take a lot of deep breaths and go deep to find the huge supply of patience that is going to be required to see this through. This will seem like it takes absolutely forever, so prepare and pace yourself.
If you are a spiritual/religious person, you are going to discover unforseen depths and challenges to your faith. Check out http://www.rejoiceministries.org/ and see if you find something helpful to you (you can sign up for free daily devotionals, and many of us here have found them very helpful).
Finally, come here to the boards as much as you need to, and pay attention to the advice given. The people who post here may each say things in different ways, and will emphasize different things, but I have found an amazing amount of consistency in the basic ideas and advice expressed on this site, regardless of what shows up in the box that identifies the person posting it.
Hang in there, you are not alone!
Blessings and peace, Dawn
Me 45/H 47, no kids Together since 1985; M/1992 Bomb1 (EA-OW1, age 22) 2001 Bomb2 (EA/PA-OW2, age 22) 10/2007, A continues H left 11/24/08 minimal contact, no legal action http://tinyurl.com/DawnHope1