First off.. do NOT take your H's word for it that everyone "laughed" about exposing him at work... His testimony is NOT reliable in the slightest there.. IGNORE it...
The fact that he even brought it up like that tells me it did bother him and no one was laughing much...
Do NOT kiss another man... it VALIDATES his affair.. EVEN IF you are DONE its important that you set a standard for ADULTHOOD and THAT is NOT IT... And I certailny don't know why you would share that info with a cheating spouse...
Anyways.. I suspect you two haven't even done the research on how much damage all of this is going to do do to your child either...