My wife has cheated, I need advice (long question)?

First and foremost, give yourself time! This is not the kind of thing you can get over in a couple of days. For awhile, feelings of betrayal are going to wash over you like tidal waves every morning when you wake up, and several times through the day. In 2 weeks to a month or so, these feelings will subside from overwhelming to merely very uncomfortable. But all the while, do as you said, and especially talk, talk, talk. She did this for a reason, and you need to competely and fully get to the bottom of what she felt was missing in the marriage, no matter how much it hurts. Don't be afraid either to find out from her what her thoughts and feelings were when she was flirting with the guy - these will give you both clues to what she felt was missing.