Advice regarding Hindu divorce laws

Hello sir / madam my name is Surabhi Singh . My brother got married 2 years ago with a girl named Punam. My sister in law 's father was a SI in Bihar police ,this year he retired from this post only.the marriage was arranged and my brother was not allowed by her parents to talk to her wife before marriage even after the marriage was fixed. There was dowry in the marriage also. Right after marriage my brother and sister in law started facing understanding problem. The issue was she began disrespecting my mother because she was having over expectations from my brother and my brother didn't know she was nearly illiterate neither we knew. She don't have any decorum how to talk and moreover she doesn't understand what we are trying to say if it is opposite of her preconceived view. Her brother started snooping via Facebook to my brother's office as a result their relationship soured more and more .out of embarrassment my brother left his fulfilling job and moved to our parents house where he is working at a lower salary. Not only this whenever my brother used to fight my sister in law's parents used to verbally abuse my mother as if my mother is provoking him to fight with her. when they were living alone the fight was there on petty matters also and all blame and abuse gets shifted to my mother because my sister in law has habit of not telling the whole matter to her family. She presents them what suits to her temperament so that she remains the victim. My brother came alone for living with my parents due to daily fights leaving his career.he came alone because if my sister in law and her brothers knew they won't let him threatening to beat him and file a case.after staying with her brother she came in our house in the name of reconciliation with my family. After coming she never tried to reconcile with my brother and at last this responsibility was also shifted to my mother . My mother is trying hard to pacify my brother but she has no patience. Even if my mother tell her something regarding Daily chores at home she starts shouting calling her father and her father mindlessly abusing my mother and always threaten her that he will put whole family behind bars. And my mother is not saying her condition to my brother so that relationship doesn't get soured again. The situation is looking like we are under the constant fear of going to jail. Please give me advice how to handle this situation and if you can help further it will be appreciated. Pls help