There's another site called Marriage Builders. Some of the techniques are a little extreme, but people have had success using them. The site caters primarily to people who are going through or contemplating divorce and those who are trying to prevent a divorce.
Did she give you any details on where she met this guy and how it started? What was she getting out of the affair other than sex? Are you away from home a lot for work or otherwise engaged in other activities?
One thing they say is that you need to "expose the affair" to everyone. Her friends, your friends, her family, your family --- everyone. It's a blow to your ego, but affairs thrive on secrecy.
One thing you MUST do in order to save your marriage is to have accountability for both of your actions and the time you spend away from each other. How was this able to go on? How did it go on inside your home without you knowing? Those factors need to be taken into account. Did she all of a sudden change her behavior?
[url=http://www.marriagebuilders.com]Marriage Builders - Successful Marriage Advice[/url]