Punch. In the face.

key his car or something.. & lock your wife out of the house then change the locks.

Is your boss John Ensign or something?

You DID get a big promotion! To CCO, that is. Chief Cuckoldry Officer. That should come with a big raise, lots of unnecessary out-of-town travel, free Brazilians for your wife and a nice hat to conceal your horns. Congratulations! They say behind every great man stands a great woman, but in your case the great woman kneels down and blows your boss.

you should have shown your bigger smile while stompping on his head

What a looser. What kind of person needs to rub something like that in someone's face to feel better about himself. Either he has the smallest dick known to man or he is a complete twat. Can probably get him fired for creating an impossible work atmosphere (not for sleeping with your wife but trying to bully you about it since this is what this is) or at least get compensation if you leave.

Knock him out and staple a piece of paper that says 'Im a douche bag' to the back of his head

I think you should go "Joker" on him and make sure that smile stays on his face.

look on the brightside, at least you didn't get fired.

i hope you beat the shit out of him with that smug ass smile of his.