Why did my brothers friend just attack me in the pool?

Ewww ewwww ewwww !!!!! Nasty, well what happened is that we were in the pool and I was on my floaty and my brother kind of pushed me off , so I fell but like not hard and anyways my bros friend was behind me. AND well I fell on him ... But then he humped me, like wth!!!! He's a freaking perv man!! And then after I was yelling and saying get off so he eventually stopes touching me. Then a while later I was floating around and I didn't know he was behind me and I accident ( he was probably planning it) kicked him between the legs . And he was all like hey she kicked me there..... And then he whispered to my brother that it felt good though. But like omg I feel violated now he's a disgusting freak that wants to get in my pants. And when ever my parent aren't in the room or around he starts touching me and you know... So I need help what do you guys think of this?? Sorry it's long but I had to say it. ;)