why?

why does it always end with anger and shouting? i'm so tired of my dad telling me what to do, and of him assuming i'll just do it and shut up. sometimes i feel myself slip so close to just snapping, like tonight when he says i'm up to late and he'll take away my computer for a week if i don't get off, all because he doesn't think i'm listening to him, even though he interrupted me to shout at me. I just hope that i don't snap, because it'll end up with him laid out, i don't sit well with stupid critisism, and i don't take it from anyone except him.