Custody of child

Respected Sir, This is regarding the safety and protection of my 3 year old son who was taken away by my wife 6 months ago. My wife tends to get into arguments and harasses me mentally for every little thing and makes it a big issue out of it. This happened for 2 years and I requested her elders to allow me to take her for marital counselling ( For which she was completely reluctant to). With her elders permission, when we went for counselling she was diagnosed of Histrionic Personality Disorder. I seeked their( her elder's) permission to allow me to get the treatment done for my wife for which they denied. But still I continued to live with her as I had no other option of getting the treatment done for her mental disorder. Now, its been 6 months that she left to her mothers place and they (my wife and her mother) are not allowing me to see my son. I believe that this is a case of mental harassment for both my son and me. Initially, when I visited their place to see my son, I got to know through my 3 year old son that they are abusing me ( I also have the video clipping of the same). So, I request you to kindly suggest me as to how do I approach the court of Law and whether the Law could be of any help to me in getting the custody of my son. Thanks & regards, Sudhakar.