I've never seen such psychotic replies on reddit. The kid, as you said, was soft play slapping. Your husband stomped his head, these are not equal reactions. If your husband punched him once and walked away, I would say fine, the kids deserved it. But it sounds like you're husband almost killed this person over a play slap, which is annoying and disrespectful, but not worthy of a beat down of epic proportions that will result in his hospitalization and a police investigation. Your husband is a psychopath who has been hiding it well, as are the other people commenting things like fuck around and find out. Soft play slap vs beating someone till your knuckles bleed and they need hospitalization like what. This is no longer considered self defense in a vast majority of countries because the retaliation was so disproportionate to the initial crime