How can I help my mom to get divorce ?

I am 17 year old wanted my mom to get divorce, because from marriage she is getting verbally abused at extinct and sometimes physically also . After her marriage my father , he ill-treat her every time, used to mistrust her saying u having affair like things ,when my mom was pregnant he used lock her in room and having daughter he was not happy things got worse by the way he is addicted to alcohol like 15-20 days he stop working just drink at home disturbing whole family like abusing verbally don’t let us sleep for night we having school next day then he sleep whole day and at night abuses now its 17 year she is surviving and not able to move out because not had support maternally and she is only graduate so not independent but she is getting punish for things she never did and hear things which don’t has her fault . She is ready to move out now but then she thinks of us (me and my sister) about our education and all as she is not independent.