I’m not sure what to do.

I was at a game at my school, and the guy behind me put his hand on my side and kept going up even though I told him to stop and I slapped him. But I delayed I don’t know I was in shock I didn’t know what to do. It got to the point where his hand got to the bottom of my bra and I had to move. His girlfriend was sitting next to me, she’s my friend but she did nothing about it and she saw the whole thing. The next day I was waiting for my other friend and I had headphones around my neck and he came over and held them as he stood in-front of me and my locker. So I had to go under his arm to get out again the girlfriend did nothing. I told some friends but, he is the type of guy that touches everyone in everywhere so none of them seemed phased or concerned about it. Am I overreacting?