Keep trying to find a way to find out the OM's wife. Either their address, her name, phone number etc. etc..
Maybe others on here can chime in with ideas..
YOU NEED TO CONTACT HIS WIFE.......
Before you do contact her you will need to gather all your evidence of the affair.... Copy of emails, the photos, etc..
Then come on here before you drop the bomb on his wife. You need to have this plan down to perfection. You will only get one chance to do it right.
Does anybody here have some ideas for Fracefc in finding out either her address, phone number or email???....
I think your best chance right now is to expose this affair and blow it out of the water. You need to call his bluff and see if he runs back to his wife if she really doesn't know. You need HER to tell you she knows or doesn't know.