I also forgot to mention...TELL HIS WIFE you crazy fool!
Do it delicately, and anonymously if you can...I really think you need to bust this secrecy up and confront your own wife.
If she has agreed to end the affair then she has to BREAK OFF CONTACT. You can't end an affair and leave your affair partner hanging around like a house pet..it just doesn't work.
If your spouse has agreed to reconcile she must agree to not contact him anymore or your efforts to work things out will be seroiusly compromised...a seriously uphill battle...similar to what I am fighting myself.