I think it is of great importance to find out if their is another person. My sitch went from "i never loved you", you need to move on... full speed ahead on divorce. to 2 weeks after exposure "I can't see my life with you and I can't see it without you.. to 6 weeks after exposure - I know we have something special and I am going to give my best to you forever (and the actions to back it up) 12 weeks - very happily married, extreme remorse and now 2 people who understand how a great marriage has to look.
I found a hand written love note buried in our garbage to bring her affair to light. My W got sloppy once I said I was done (trying stuff that didn't work) and meant it. I truly believe exposure played a critical role in our reconcilliation (OM made a real quality introduction to W's family by emailing them how a good mother, sister should "feel" about their relationship) Nice one douchbag!
Combine that with some hard work, change, fear of loss and wisdom on your part and your things might begin to look in your favor.
You are getting some great advice here by the best this site has to offer. Believe it, then begin to live it. You will be rewarded regardless of what you W does.