WHAT SHOULD I DO?!

Okay I only a teen (13) precisely, so please bare with.

So a wee while back two boys at school were nice to me. We got on really well and became sort of friends, everything was fine.

Then one day the boys were mucking around a bit and got a bit carried away with themselves and started being silly to me. (Pretty usual for boys right?) Anyway one of them came over to me and kept on grabbing my butt. At first I asked him 2 stop but he just then slapped my butt many times.

I then just ran off but, the chased after me.

Then, the other one grabbed me and pinned me against a wall. I tried to break free but he didn't let me go.

Then he stared making sexual noises and the other one was voice recording it. They then sent it out to all of my friends. I know this isn't acceptable but how bad is it???