I think you need to sit down with him and have a real talk. Tell him a story. Tell him that he and his friend were walking down the road and found he found a cool rock. His friend had a hissy-fit, screaming and crying and acting like a big baby. His friend's mom had to take him home and put him in his room.
Ask him why his friend would act like a little 3 year old. Let him tell you what he thinks about your story.
T., you need to start giving him hard consequences for these outbursts. When he calms down, take a precious toy or usual privilege away. Tell him that the more he does this, the more you will take away.
What you described about him doing to his friend is rather serious. You need to stop allowing this by punishing him for it.
Dawn