You have a couple of options that I have seen work from past experience...
1) act perfectly happy with your life. Agree with her that divorce would be the best thing. Pursue the divorce FASTER than she wants to. and act like a mature, confident man who is going somewhere with his life and is anxious to get there with or without her...
2) this is another option.. expose the affair to his wife, his work, your wife's work etc. etc...
A lot of times when the OM is having an affair and his wife finds out about it, he will drop YOUR wife like a hot potato. I know you said he was getting a divorce, but he could be lying about that to your wife. Don't tell your wife what you are doing. Once your wife finds out she will most likely be furious. So be it. Your marriage can survive her anger, but it can't survive with a 3rd person in it.....
In the meantime, just be nice to your wife, don't be overboard with love or affection. Just be nice and in your own world. Don't act unhappy or angry or upset. Life is good. Don't talk about the relationship. If she brings it up, just tell her you hear her loud and clear.. "you want a divorce, I understand and agree that divorce may be for the best. Let's get it done with..." (THAT is how you validate a person.agree with their stance and shut up.. trust me they feel heard and validated when you just agree)
when you take that type of attitude and position regarding the diovrce, usually THEY suddenly slow it down and hem and haw. It actually works FOR you when you act like you WANT to pursue divorce. It gains respect for you. Suddenly they aren't so sure it is what they want.
