If a married man feels really bad about having an affair with his friend does that mean he wont do it again or would he once he has time to stop feeling sorry for himself?

First of all when two people are friends, they have this respect for each others. But when this friendship is broken and it become more intimate that's when the respect is set aside. The respect turn to lust and the friendship becomes more personal to both of you. Maybe he did felt bad, who wouldn't if the two of you were friends before. Now you become his "Friend with Benefit " Maybe his feeling bad but not bad enough to feel sorry for himself.