Want to save my parents, my son and myself from my wife violence

In the year 2010 we got married and lived separate from my parents, far from my native. In the year 2014 my wife and his entire family ganged up and file a 498A against me and my parents. the case was dismissed by our mutual consent and counseling. She said that it was happened due to some circumstances and doesn't realize the impact. Now she want to come back with my 2 and half year old kid. I accepted her after long discussion. She realized her mistake and came back after few months. Since then she is continuously threatening me without thinking anything about my child future. I loved my child so much i don't want to left him with such careless mother. Past:- Before marriage my wife had a affair with some local guy and left her own house with that guy. This was cleared before our marriage and she accepted that it was her mistake. We used to work together in a same company, there one of colleague proposed her for marriage and they chat for sometime and finally refused. Then one day she proposed me for marry, and finally we got married on 2010. Present:- Now she had some relation with Kolkata Traffic police surgent which I caught but can't do anything because she keep threatening me. Please help I'm not able to concentrate my work and daily life. My child is affected lot because of this. She is demanding frequent visit to Kolkata from Pune without thinking my child career.