Married to a wealthy and family with legal background and political connection

Right after birth of my baby, verbal abuse turned into physical abuse. My inlaws are all lawyers and judges(suspended with criminal records) My husband didn't let me work and now tells me i won't get custody because i don't have income. Also threatens to beat me(have whatsapp chat) and if i try to take legal help, they will delay things by filing false cases, also refused to pay for me and my baby if i don't go back to him as i came back to my parents. My father in law being private lawyer hides income and they know how to do all sort of illegal things. I am afraid of them. There are also indirect demands of dowry, from the time of marriage, humiliation and insult if we fail to keep up, and then also expecting me to smile and talk to them. How to get back my the money we were forced to spend(gifts, cash jewellery, marriage in resort they confirmed) what proof do we need to acquire? We didn't keep receipts as i didn't know love marriage will turn bitter due to inlaws continous monitoring and manipulation.