Exactly.You have completely missed the point. The firmness with the other man has nothing to do with wife deterring. It has everything to do with a man grabbing my wife’s ass right in front of me. Based on what the OP said the wife would already be pretty much scratched off my list already. I’m not a violent dude but that interaction needed t be handled up front.
The dude gets "his fingers broken" for disrespecting me.
Same way as if an AP knew the cheater was married. It's a separate affront from your wife/husband being a lush or a *****.
If it's a full-tilt double betrayal (like best friend) then that is even more aggregious.
I see people say constantly "they didn't marry you" in reference to an AP, nope they didn't but they sure disrespected me. It does not have to be one or the other (AP or wife), It can be both that deserve consequences.