DS#1 has started purposefully hurting his brother. He will do something to him (for instance, today he threw dh's work boot - size 13 huge steel-toe workboot - at DS#2), then run away with his hands over his ears (cuz he knows the baby will start crying) and a mischevous smile on his face. I just don't know what to do. It makes me so mad. It's very rare that the baby will play happily by himself, and when he does DS#1 ruins it by hurting him.: I try explaining that it hurts DS#2 and makes him sad, but DS#1 just doesn't get it. How should I go about handling this?