However, if he was willing to be honest, show empathy for his actions, confirm OW was out of picture and have a true desire to work on M then I think I would accept that.
If there is an affair and the other person ends it, you must insist on transparency. He has to be able to show you that he is not in contact, on demand -- email and phone unlocked and available to you, you handle the cellphone bill so you can check for suspicious numbers, etc.
Is it an invasion of privacy? He broke his commitment to you, and needs to make restitution if reconciliation is going to work. It's more of a matter of rebuilding trust, which will require verification.
Me: 44, Wife: 39 M: 17 years T: 20 years Bomb on 08/25/09 1/13/10: MC started 1/28/10, 2/8/10: More bombs 8/28/10: Wife moved out No talk of D, no movement