Find out if the MC is marriage friendly. I know this sounds like a no brainer, but my own experiences with MC didn't go so well as the therapist was a victim of her own divorce. There's a section on finding a good MC here on the website.
Read Divorce Remedy as quickly as you can, then repeat. Do not try to get your wife to read it, and don't let her know you are. It's OK to work on this on your own for awhile, and trying to get her to go with your program probably won't work anyway.
Breathe!
Take a look at the chapter on The Last Resort Technique. You probably need to apply some of that first. As hard as it is (I KNOW!), you've got to stop the pursuit, and stop looking/acting like an emotional mess. Hard to do when the world is falling in around you, but the sooner you seem strong and like your old self that she fell in love with, the sooner you can start making little bits of progress.
Consider some DB phone coaching. It's really worthwhile.
