What do i do about my sister/dad?

hi. my dad has a temper and doesnt really think wen he is mad. my dad has hit my mom, battered and pushed her around once, hit my sister, grabbed her neck, pushed me against a wall, and has verbally abused all of us (we are miserable, no good women, etc.). and wen he is mad he doesnt give my mom any money so we have to last off of her minimum wage. he's left many times ranging from a couple of days to a month. i think im the only one that really is bothered by all this. i try to reason with my dad and he says i am lying or tells me to be quiet cuz its not my place. my sister has the same type of personality i think. she's broken down my door trying to beat me up, given me a bloody nose and many many bruises, and spit in my face. my mom says that they just are quicktempered and cant help it because its genes. she treats the whole situation like it is nothing and jokes around about it. my mom doesnt like my dad but pretends she does. he will be nice for a couple of weeks & she will cont