First off. When I said beat the living shit out of the son I didn't literally mean take a iron bar and beat his brains in like the son did to the other kid. If you really thought I meant a beating that badly, you need some common sense.
Secondly, nowhere in OP's story did he mention that son was defending himself. Im pretty fucking sure when you take an iron bar and hit someone in the face with it, its usually not defense. How often do you get jumped by someone, happen to find a metal bar and then hit them in the face? HUH? Not pretty often I bet.