5year olds behavioural problem?

I donr know wats ailing my son yesterday he came bak quite pissed out frm ckool.the girl who sits next to him in cl poked a sharp finger tip on his hand as he had kept his hands on the desk on probing further he told that they were playing and when it ws his turn she quickly removed her hand frm the desk.i told him it was the wise thing to do since the pencil tip may harm her but my son feels everyone takes him for a ride ...and he likes all nonsense games like first A hit me in tummy when it was my turn they start telling Maam ...i dont know wat 2 do...at times he will b hit first and if he complains he tells me that the kids gang up and say that he hit first ...i know he isnt telling a lie always cos i can judge when he is rite and when hes wrong.Gawd i m so pissed up as to wat 2 to tell him and how 2 make him a confident no violence guy....