Issue with wife for blackmailing

I am having issue with wife. It has been 4 years of marriage with a 2 year old son. Within 6 months of the marriage she left the house with the argument that she cannot cooperate with my parents as she is a working woman and need her space. She also put forward a condition that since her father lives all by himself, which will keep her tensed so she will stay with her father. She has been blackmailing me ever since for some reason or the other. However, she does not want to end the relationship either. Later, after one year she along with her family convinced me to forget the past and move ahead so one fine day she came back on her own. I was unaware that she had other plans as she does what she wish. One month after her pregnancy she left the house again and has been living with her father. She always willingly picks up fights which became physical at the end. She have filed a complaint which was not registered but was told to stay away from her and the kid. I have not seen my kid ever since; what should I do? I have already asked for mutual separation but she is not cooperating. The marriage was based on lies as she hid her age, education and her past. Her house is just one lane after mine and I have living here for 5 years just to take care of my aging father and prior to this I was living in a different city.