Hopefully this will give you some more hope. My aunt has been married 20+ years. Her husband had an affair (not sure for how many months) but she found out about it approx. 10/1/08. He moved out and into his sister's and OW also moved in with him.
Just before Thanksgiving he was a wreck, and asked to come home. He was willing to go to counseling, doctor, etc.
Just received an update about a week ago. My aunt allowed him to help OW move to another town and the affair started again.
Moral of the story (I think)... concentrate on the future. Realize that they have to take this path, and when they come crawling back (which is what we all want)... have the skills and tools necessary to help them come back and build a stronger marriage.