Advice on consent divorce for my sister after 10 years of marriag

Am writing this question with respect to my sisters marriage life. In 2004, my sister got married with my uncle (Who is close relative, He is son of my Aunty). My uncle is working in TN police as writer. First 01 year their married life was smooth. From 2nd year onwards there is issue that coming with them which resolved with family discussions. My uncle has drinking habit and also has affair with other women in near his police station. Due to this issue my sister use to flight with him repeatedly. Since my uncle is close family relative, my mom and dad not taken this issue very seriously and think that issues will solve soon. Also as per my understanding My aunty (Mother in law of my sister) has not taken this issue very seriously and i feel they use my uncle income and engery for their own family purpose while isolating my sister. Till date i dont think so my sister got basic need of wedding and her rights of marrige life including child. During this marriage i was just 15 years i dont have any idea. Now am settled with decent job and now i want to resolve this stupid issue immediately. Kindly note my sister was marriage proof as follows 1. Her name in their family card (No separate card applied since he is not agreeing ) 2. LIC policy with his name added as spouse Now my uncle is completely addicted to drink and not regularly going for job also. Now my sister also not ready to continue this life and want complete relief. But i feel that my uncle will not agree and co operate for this process. So i require fair advise to close this issue Thanks