Sick and tired of my family what can I do?

Sick of it now, sick of them mouthing off at me. I am 16 everything I do isnt good enough, my dad is a mardy **** I just wanna smash his face in. Its making me really angry he repeats himself and when I tell him he doesnt listen then that causes a row and my mum defends him. My sister has 2 kids and takes advantage of my mum and my mum whos partially sighted has the kids during the day and sometimes over night 2 or 3 times a week. I am getting really annoyed with my family I wanna just smash my head off a brick wall. My lifes going now where and nowere fast. I am only 16 and still at school I just wanna leave but I carnt with no place to stay. The only thing thats keeping me sane at the minute is my pet cat.