My father is a piece of shit to me and my mom, what should i do

He acts like a great person in front of people outside of his family but treats his family like shit. He keeps nagging and disrespecting me. And when i stand up and defend myself he only gets worse. I just want him to stay away from my life i hate him, i hope he dies. The only way i can deal with this piece of shit is just stay quiet and never communicate with him and say yes to whatever he says like a robot. Idk how people like these exist irl, i was throughout my childhood just stayong quiet, never talk to him or have a normal convo with him, be a poker face, and even if he stays nagging or disrespecting me i leeave him barking. But as i grew older i could't stand his shit anymore. What should i do? I'm in a 3rd world country so i just can't leave my house, i'm 21yo and still studying.