Brother wife mental torture

Myself with elderly parents and my second brother and his family live in a joint family. My second brother got married 21 years ago. My Brother wife(Poornima Devi,School Teacher) and his parents insults my family members and past 7 years she acts like mentally disturbed and torturing my elderly parents and behaving rude with me. Due to her insults I stopped talking to her almost 12 years and I d o not involve or interfere in her activities. But she periodically insults my mother and uses harsh words against her. Due to my mother age and being orthodox my mother keeps calm and gets worried and she is diabetic too and my mother does all household work. Past 4 years my brother wife behavior changed and behaving rudely and keeps threatening that she would file police complaint against us.My maternal uncle adviced many times to file a police complaint but they refused to do due to family name should be spoiled. Last year I had surgery after discharge my brother wife did not allow me to take rest instead she keeps TV sound loud in the late night and disturb us.My brother wife had beaten my mother twice and she attempted to beat my father last year. Now this year again such torture started, two days back I was sitting in hall watching TV and she dusted with clothes on me, I was surprised at her behaviour and she turned rude at me and threatened she will take picture and file a police complaint and her elder son(Darsan) was watching all this scenes but kept quiet. I am afraid of her behavior and mentally disturbed.Neighbours also suggesting to give police complaint but my parents are refusing. How do I safe guard myself and my parents