Request for Advice - Family Issue

My spouse along with her family is emotionally blackmailing me and my aged mother post delivery of my son citing flimsy reasons and issues leisurely ignoring all their mistakes they have committed and still committing. All this time, We had looked after her well and also took care of all her expenses including the delivery and based on her wish to be with her mother post delivery, dropped her at her home which is quite far away from my home. Now, We are not being allowed to see my kid at all which is basically due to her mother's influence and post delivery, my wife has suddenly changed her behaviour. I have given her a lot of time to come out of her depression, talked to her dad who doesnt have any status in this family and feigns ignorance, and also tried to engage with them via family and some friends. What I found out was, Her mother and sister are not in good terms with most of their own family members also and there are very few family friends for them and they too said to me that her mother can become mentally unstable prone to depression and hysteria and warned me to take my wife away from her control ASAP!!! I am also aware that, going the legal route may not be a good option and most of the times, the words of the women get more heard than that of the men's, but Is there a very basic legal step or any act or procedure which can be initiated from my end to safeguard me and my family? Is it possible to seek single custody of my son who is a toddler without filing for a divorce as I believe this will atleast force my wife to get away from her mother. My intention is not at all to get separated from my wife, but I feel, there should be some fear instilled in her mind that she stands to loose out a good life and our kid if she continues to allow herself to be emotionally influenced by her mother. We have committed no wrongs and as you know, in family, small issues or tremors do occur, but this kind of reaction from my wife and her family was not something we expected!!! I am quite confident, my wife will finally understand me and my family and come back, but it is the time part, I am really worried about which are the moments, I will loose with my son. For my aged mother, he is her first grand child and these golden moments are very precious for her as well considering her age!!! Hence my very humble request for your advice. Really looking forward for your response!!!