My father is (70 aged) paralyzed he want to divorce my step mother

My name is (undisclosed) aged 38 years old and I’m an NRI living outside the country from last 14 years. I am writing this to seek further right legal guidance to take necessary action against my stepmother. My father (70yrs) is a retired Driver. We are three brothers and sisters, elder one is a sister (42yr) who is married and living with her husband, I’m married too and reside outside the country, the second sister (40yr) who is married living with her husband. My mother was a housewife who expired in 2003. After 10year of my mother's expiration, in 2013 my father got married to my step-mother, she also is second married (she was divorce) and marrying my dad was her second marriage. With my stepmother have one son (18yr) too (from her first husband).my father clearly doesn’t‎ take responsibility of her son at time of married agreed by both parties. Her son taking some kind of Drug. My stepmother is horrible and has a criminal mind. From the first year of marriage, she started fighting with sister over small things and never stay when my sister come to meet my father she went to her mother house, she touched my father every time asking money shouting with loud voice. The torcher level gets worse year over year and is unmeasurable. We all clearly know that her intention is that she does not want us to be around so that it will be easy for her to occupy the property. She is divorce women, they torcher her first husband also that’s why he leave her with one son, her son is addicted from some kind of drug. when I went to my father home to take bed for him that time I clearly told her we will live together in other home, her mother also with her, she also agreed that time, she told I will go for marriage function after that I will come, I said ok, I went outside, I was come back for something I heard from outside the window her mom and my step mother planning for something else I got shocked, her mother was teaching her don’t go now if you are going now tell I am missing my son and come to my home, he (my father) daughter and son how many days will stay 15 days 20 days after that you go and take your son also together and I heard my step mother said my father is not dying ( step mother said) (MAR TA BHI NAHI HAI). My father is sick last 3 months she didn’t came to take care him, just come twice, 1st she come after 15 days approx. she come with her mother and sister, she drink tea and gone not even ask my father how is he, not sit beside my father nothing, 2nd time she come for the some file she take and gone said after election I will come, but she didn’t come. After 2 months when my sisters gone she got information from outside my sisters gone then she come for living with my father, I asked her why came now after two months now no need your support. Her mother said bring your four people and our four people sit together and decide. after that I called them to come for talk with four people her mother said you people come to our place I clearly