This boy is dating my Best-Friend is dating and well the other day he..?

The other day at Luncchtime this boy that is dating my best-friend started slapping me in the chest and my with this headband with a metal end on it. He also used it as a slingshot. In the giadance counselour he said he wasn't trying to on purpose. He hit 2 other girls with it! Then, he called me hot and said it's my fault for growing . My friends even heard him say that! What should I do and what does this mean?