Custody of child

Hi, My wife and I have been married for 9 years. We have a 5 year old son. We're a muslim family from kerala, residing in bangalore. There has been issues in the marriage since the beginning with her only wanting to focus on career and unable to offer companionship or consummate the marriage due to health complications. After 4 years of medical help, we finally managed to have a child. We probably would have attempted sex a handful of times since. While we sleep in the same bed, there is no physical relationship due to my wife's health complication. This has been the case since day one of the marriage. During the nine years, both of us have had considerable growth in our careers. I left a high paying job abroad so that I could be here with him as he was too young to relocate at the time. While I try and not be busy for the child and go out of my way to make sure he has a good upbringing, my wife refuses to focus on him and is often very harsh in her behavior to both of us. She hurts him physically and tries to get him to do everything himself so that she doesn't have to. Most of his chores are done either by me or my parents. Right now, she is visiting her parents and in the two days they've been there, my son has hurt his head twice, one time requiring stitches. Both of this happened due to sheer negligence as she doesn't accompany him to the toilet. I do when he's here with me. We've had multiple fights due to her neglect of him and several times in the relationship she has spoken about separating and once even threatened that she will level domestic abuse allegations against me or something similar against my parents. My parents live with me and have to bear the brunt of her rude behavior towards them, however stay quiet so that our son is not affected. I have not said yes to a separation because I cannot bear the thought of being without my son. And she has made it clear that she wants him to stay with her even though she doesn't spend time with him at all and treats him like an experiment who needs to brought up on a strict diet etc. There are several such instances but I do not intend to defame her as in every story, the writer is the hero. So I'm sure she has her reasons. My primary question is, what are my chances of gaining custody of my son if we decide to separate? I don't have issues with her visiting or spending time with him but I cannot bear the thought of him not having me to protect his interests while she is busy ignoring him. She is not a bad human being, just that her interests are elsewhere. However I cannot let my son grow up without a beautiful childhood. I am also worried about false accusations of abuse etc. Have read several horror stories where the law blindly favors the mother. I am willing to keep quiet and bear this if there is no hope as I'd rather my son be safe and cared for than focus on my happiness alone. Looking forward to your valuable advice. A concerned father.