Terrible two? Or one?

I know it should be two, but how about for Peter? He is so frustrated everyday that now i am terrified by his screaming. I hate to see him upset, but it is really not easy for me to keep track of what he wants every other minutes. I miss those days when he would laugh loudly and seemed to be consent all the time. Now it becomes a luxious second in daily life.

This morning after I put him on the floor, right away he went up to a bigger boy and tapped on the boy's head. Before I realized, he was in front of another little girl and tapped on her. At that point both the teacher and I began to say"be nice, Peter""gentle, gentle.."But he already did the tapping with his palm two more times. I know that he can not understand it hurts for other kids, and he might have his good intention, but he is definitely requiring full time close supervision to avoid possible undesired accident.

I know that this boy is going to make troubles at school for me soon. But i am not ready, what shall i do?.....