The 2nd time something like this has happened.... how many more?

Well my brother is two years older than me. Im 16 hes 18. For those of you who dont know im a girl =P.
Well about two months ago I had just left my room to go to the bathroom and there is my brother on the landing. He starts play fighting with me but I wasnt in the mood to so I asked him to get off me, he wassnt listning so I shouted get off at him. He instantly releases me and I walk to the bathroom where then I hear him heckling me calling me fat.
When I was younger I was always bullied by my weight andd looks and he knows how urt I get when anyone mentions it even jokingly. But this wasnt jokingly.

So I tell him to shut up and just then he grabs me by the arm and twists it behind my back telling me he doesnt take orders from girls. So then im squirming to get free and Im not exactly the stongest person so I slap him and he pins me over the banister on the stairs swearing and chocking me. My mum cmes running up the stairs and shes smaller than me so she was screaming and hitting him to get off me and eventualy he does. He then recedes into his room and so I do I crying my eyes out. I had bruses arround my neck and up my arm for about a week, try explaining them to teachers at school.

And this is the most recent.

Yesterday I was brushing my teeth in the bathroom and my brother walks in to wash his hands so I move out of the way of the sink and sit on the baths edge. And he leaves and I stand back up and continue to brush my teeth over the sink and he comes back in and fills up his glass with some water and then holds it over my head. I jsut look at him and say 'dont' So what does he do he pours the whole thing over my head after I had jsut straightened my hair. I turn round and look at him and say 'why did you do that I have to go out in half an hour!' he starts oo'ing at me and grabs my wrists saying 'whatcha gonna do now' So I try wiggling free proving I cant do that he sees this as a perfect oppertunity to threton me. he holds his fist to my face and starts swearing in my face telling me to never fight back and that im worthless and ugly and fat. I start to cry and so he pushes me backwards and I fall into the bath. I have a bad back so this didnt help. And my dad and mum run up the stairs after all fo the screaming and my dad thretons him that if he ever lays a hand on me he will hurt him (Well some more graphical terms used but not mibba friendly) and so here I am again beaton up by my brother again hw many more times?

I feel sorry for who ever ends up with him.