How to get my child back from my cruel wife

Hi there, I married before 6 year and i have 4 year old boy. From the day one of my marriage my wife used to fight with me as we have very less understanding between us. Gradually my wife have started doubting & blaming on me about my extra-marital affairs. she always tried to humiliate and abused me, my parents and use to beat me with Rock, and also humiliated our reputation in society. I was suffering from GBS from past 2 year, After coming home from treamtment she don't want to take care for me, so from 6 months my wife went to her parent's home for holidays; from there also she used to do doubts and all the things. Than i have decided to not to bring her back into my life as we are never going to live a happy life together. So from last 6 months she is living at her parents home. During this time she has sent different applications by a lawyer at Women's police station against me and my whole family with fake charges. And threaten me and my family for my child that she won't let me she him ever. But me and my family loves him so much, his brother and mother are criminal of mindset they keep guns, I'm scare of my son's future.they always use to threaten my family, spoiled our reputation in society. Than, when i asked for divorce than she refused for the same and she asked me to take her back at my home. She said she doesn't want alimony or doesn't want to file a case to court; but she will also not give divorce and my son to me ever at any condition and said she will not let me go ahead in my life as her revenge. Will make sure that me and my family cry every second. Now i want to keep my parent safe and happy , How can I get DIVORCE from my cruel wife and her criminal family and get my child back from?? & what if i go to other country like USA?? (NOTE: We haven't registered our marriage to any office or we don't have any marriage certificate or documents which proves that we are married.)