Maintenance money from husband.

I am a 52 year old housewife having 3 children, two daughters: aged 21 and 20 and a son aged 17. I have been married to my husband for more than 20 years and he is the only earning member in the family. He had affairs with a lot of women before marriage and even when I was pregnant with my first child, he used to go to other women's home and threatened to throw me out of the house if I ever said anything. While my 3 children were growing up, he used to fight with me and used to beat me. He never gave me or my children any money and the reason he gave was that he was giving us food to eat and paid the school and college bills. Our expenses for clothing and medical care had to be managed by me. He is probably having an affair with a phd student in his department and even got a written anonymous complaint in his name to the vice chancellor of the university for spoiling the decorum of the department by having personal relations with students. And when I asked about it, he kicked me and pulled me by my hair saying I was the one who wrote the letter. He called a lawyer saying that my wife is a prostitute and I dont want to live with her. Now he is living in his sister's house along with my elder daughter who wishes to stay with him. The other 2 children live with me in his house. My question is, I want to demand maintenance as my younger daughter and son are still studying and I will not be able to support their studies. My husband is a government employee with a salary of 1 lakh 90 thousand per month. How much money will we get in maintainance? And will we have to leave the house as the property is in his name? I don't have anywhere else to take my children to. How much time does the court procedure take? And will I still get money if he files for a divorce? He is using my elder daughter and filed a fake complaint saying that I beat my daughter and torture her. He has even tampered the affidavit of my previous engagement which did not work out and my husband tampered the date on the divorce affidavit, thus claiming that I was already married when I was with him.