Giving me assignments is pretty silly. I won't be playing that game with you.
Of course we all make mistakes. But we don't all make that one.
I have no doubt that he has made things right with his wife and that's all that matters. He did not hurt me, so I have nothing to "forgive" him for.
It's between his wife and himself.
Still, married men should keep their pants on unless they are with their wife.
Something tells me that you have been more than just a little bit tempted at least once in your married life. You said you have never strayed and I believe you, but you must have come really close to have feelings this strong about the issue.
I'm not meaning that as a flame or anything. Just an observation.