Children are different in school lots of times than they are at home. So believe me on that one. Also, I really don't know what to do about the strong behavior. Maybe he needs to spend some quiet time with either you or Dad, and he will come around and tell you what is wrong. I read that in a book about how to discipline boys. It takes some time for him to develop confidence in you two, but if you persist, and take him aside as often as you or Dad can, then you may get him to tell you what is wrong. Something is. I saw a program on Oprah that showed an African Bush Father - named Vincent - take aside a snotty little spoiled American boy and just sit and talk with him quietly leaning against a tree. Later on when the boy got mean again - Vincent, the father of the large family that the American family was visiting - took the boy's hand an walked into the 'bush' and just had a walk and a talk. That is what I am trying to explain to you and Dad.
Another thing - when he starts this, then immediately pick him up or guide him to his room. He needs to stay in there and scream and throw until he is calm and ready to be with the family again. I had a little boy in preschool that did that a couple of times, then he calmed down and really loved me. He changed to a different happier child. He truly had a serious problem at home. His mother's family did not 'like' his father, and therefore treated him very badly - his name was Earl, a darling boy. He wanted to come home and be my little boy, he told me that, and he was only 4 years old. I still think about him, and that was about 30 years ago.
Also, take him outside and have a lot of tennis sized balls and you and he make a ball throwing game against a big board or something that can take the pounding. It will help him, really, it will. ....and it will help you too. Because you will be getting closer to one of the loves of your life. I know because I had two children and now 3 great grandchildren, and my life is so happy when I am with them.
That is all I know. Good Luck, C. N.