Reply to My son has really bad behavior

Well my son's biological mother was a drug addict so I would appreciate if you didn't judge and call us lazy parents he has some developmental issues that we are working on but the problem we have is that he was thinks it's funny to watch people get killed or hurt so he won't stop bullying other kids we have tried positive reinforcement and every type punishment you could think of I always remind him he's loved and we just want him to be happy and he still doesn't care he wants to take revenge on anyone who makes him mad or upset