Harassment against wife from other family members

This is regarding harassment against my wife. I used to stay in jharkhand. We are 3 brothers including me. My first brother stays with his family(brother, wife, son) in 1st floor, second brother stays with his family(wife, 2 son) in ground floor and I used to stay with my family(me, wife, son, daughter) in 2nd floor. But these days my son and daughter gone for his job and higher studies in other state. So only me and my wife stays in 2nd floor. The problem is whenever my wife use to come through stairs in 2nd floor the son of my elder brother always use to give slang languages to my wife which is like a mental harassment. And also give threats to do something wrong against my family. And this things are going out of control day by day. So I always get worried about my family members and also my wife cries after hearing this type of slang words. I am much worried as the son of my first brother always get drunk and give threats. And moreover I haven't discuss these things with my son and daughter as it may impact their studies and career. I want to take some legal action to get rid of this. I think this is really a harassment against a women and their family. Please suggest how to proceed with legal procedures.