As for her, if you are willing to seriously talk, I will tell you anything you want to know, but she is aware I still have feelings for you.
Sounds more like "I will tell you anything you want to HEAR" to me! Also sounds like he's not telling OW the truth either... "feelings"??
I am 99.99% sure that he has not told his girlfriend the truth. In fact, I have never personally heard of a single instance where a currently-wayward spouse did tell the truth to their OM/OW about the nature of their current relationship with their husband or wife.
