What should i do about my emotionaly abusive dad?

my dad bullied my family. especially me and my mum. he sometimes takes her phone, reads her texts, stalks us down, reads myy computer from downstairs (hacks it), he also says nasty things to us. he says i should overdose and die...but then hes also randomly nice and thsi makes everyone kind of wonder if we are just being silly to be so downtrodden. i know im not explainign this well but when you live with it, yu kind of doubt its real and you dont reall see it as bad anymore. but i know its all wrong how he treats us. he bellittles me and my mother. and uses tactics to stop her from leaving. he calls me fat, he makes me feel liek a failure. i knwo u mite think that its the usually moany teen hating their dad. but we have lived with it for so long. my whole family are dpressed. i have a 9 yr old sister and a 14 ear old brother. we all are so squashed from the way he is.. he nevcer listens. he raises his voice for no reason and just shouts like a child over tiny things. we have been walking on eggshells for our whole life. if i say i wil leave he or report him . he says he will say im an alcoholic or mad and no one will believe me or take me seriosuly 9he is a lawer0 or he tells my mum she will never get a job and he will keep the kids..theres so much i could sa.we wana get out but he reads our emails and everything we do he spies on. he owns the house with his mum and my mum has tried to get out. we once stayed at a travel inn but he just manuplulates us back :( he now blames me for her wanting to leave saying ive put these ideas into my head. today he said i hate you i hope you die go overdose. all these things every day. its my life. i cant take it anymore. IVE THOUGHT OF EVERTHING. NOTHING WORKS. WHAT CAN I DO . im 17 and havent got a job coz im at college. my mum hasnt got a job coz he says she shud lok after house. its just terrible