How to deal with abusive parents?

my dad is abusve to every one of us.. my mom .. me.. and my lil and older bro.....he caslls us studip worthless alll the time and this really hurts me ALOT!!! today he broke out hittin my brother just because he went out side in the rain and i was trying to prtect him and have all the hits go to me cuz i love my brother but there was really nothing i could do he was kicking him and slapping him..there was a time when he threw stuf at my mom and called her crazy and worthless.. she works 2 jobs!!!! trying to provide for us!!! and all he does is sit on his but do nothing but eat sleep and shout!!!!...there was also a time when we live in a apartment and he gave my a rent payment to put in the managers office and... when i went i accidentally put it in the out going mail..and when i told him he started screaming at me hitting me kicking me punching me saying all these mean stuff i was only 13 at the time and it was a simple mistake now i'm 14 and i'm sick of all the abuse he has been doing to us for all these years..i need help really.. i'm crying out to everyone.. please help me.. i'm really thinking of running away with my 7 year old brother rite now if this goes on..i'm in tear just writting this seeing how much my life really suck.....bcuz of him