I found out from the OM. My w and I shared a pc and my wife left her chat client running from the night before and i hopped onto the PC to check something before I went to work.
I sat down and moved the mouse and a few seconds later
chat client window pops up - "Good Morning My Love"
BOOM, that was enough for me! I did intel for four days and then I confronted her on the Saturday morning. The creep had known her for two weeks and was already advertising the affair all over the internet.. he was shamelessly falunting it.