I can't deal with my brother anymore?

I have a brother who never stops arguing with me and when he realises he!s wrong he punches me and gets really violent. He rows over the silliest of things and is always having mood swings. Not normal teenage mood swings, but really extreme. He has lost himself a lot of friends by them. Also I have been speaking to my dad abOut it and we bOth think he is bipolar. Maybe not to that extent but it is a living he'll being around him. I don't know how much longer I can take it. I am only 16 but yet I am counting down the days until I leave home just to get away from him. I know this probably sounds pathetic written down but if you knew what o was going through every day you would understand. I just don't really know what to do. Do you have any tips on how to deal with this? Although he is just 1 year younger he behaves like a 2 year old and a violent hooligan. He is also bigger than me which is quite intimidating especially when he gets violent. How can I handle this?