Husband trying to get his son from wife.

Me and Wife(orphan) have been married for abt 9 yrs now. We have a child of 7 yrs old. My wife is always influenced by her elder sister, who lives with her children most of the time as her husband works in another state and visits once in couple of weeks and mother-in-law stays a couple of lanes away and does not really take care of her. My wife always goes to her sister house when i sometimes object her, she will make a big scene out of it before living the house and tell her sister that i have trashed her out. Initially stage of marriage the elders use to settle the matter but now, even my parents are feared of talking to my wife and her sister. In recent times due to pandemic I had to come to home town and stay with my parents and she feels her freedom is lost and getting really irritated. I explained her many times about the bad situation and I might loose my job also and literally requested her to understand & stay with me, share responsibilities, take care household activities, son's education but she wont understand. She does not provide our son with some basic needs but made him addicted to mobile instead of making him study. I too allow him use mobile sometimes but restrict him from playing games or watch youtube for videos like rude/offensive/impolite. she wants her son by only intension that I will adjust with her for the sake of our son at least. After many times she leaving the our house for silly reasons and coming back a 2 or 3 months. Till today while separated, my son used to stay with her mother and we used to bring bring him home for couple of days and return back. Recently in Feb'21, she left again, took a step further and not allowing me to visit/stay my son. She immediately locks herself with my son inside her sister house and her sister will threaten me from entering house. I want to know following. 1. How do I get my son back? She cant afford to take care of our son daily needs also. But to punish me she is not allowing me or my parents. 2. During final exams, after discussion she told she will make our son prepare for final exams but when I saw the hand writing of my son's answer sheet, I realized she cheated exams as well. She least bothered to prepare our son for exams. 3. How to defend myself from her, as todays laws are always in favor of women, which my wife is taking advantage of. She always threatens to go to police and lodge complaints of me beating, teasing, trashing her. 4. She in the past had to attend court in some case related, which I came to know later, how do I get info of it. 5. She demands staying at a different place and not with my parents. but she conveys in such a manner that their is no proof of it. 6. In the past, she sold a part of her land and when I asked her she made a dispute and left. After returning I never asked about this again. Shouldn't she be helping a bit in our financial matters at least. Is it only husband's responsibility?