I don't have advice about the confrontation but I am just so sorry you have to deal with this. Walking away is one thing, affairs are another. I dealt with an EA two years ago and it was soul-crushing and also why I think I have so much resentment towards him now. I don't know what else to say except sorry. Hope the vets chime in soon regarding advice.
Me 35 H 34 DS- newborn 8/13 T 8.5 M 7 H's EA - 10/11 INILWY 5/13 DBing 6/13 Don't know WTF to do 1/14