Advice what step to take and how to file.

This is Mercy from Bangalore. I needed some advice, I have been married for 6years went through a separation early months of marriage due to interference from in laws.. then after 3 years my husband joined me at my fathers place as he was almost sent out due to property issues. We were peaceful, was blessed with a child then, who is 2years now, conceived again in a short span and have another child who is 7months... but when I was 6momths pregnant my in laws again interfered causing problem, and I was going through depression as my husband was not by me to understand my turmoil. At the same time he had restricted me from marriage not to have any connection with my mother and her family as they were unhappy about the proposal but it was my father alone who came forward and stood for this marriage. He left me blaming me that I sent him out, while I was deeply broken he didnt understand my pain when his sister challenged to separate me. Ever since the time he left me when I was 6months pregnant he just comes once in awhile, any small confusion he avoids us fully. Now, I\\\'m pregnant for the 3rd time and 3 months. He tells me I have to join him and puts all conditions against my mum. But when he was not there I had to spend few days with her so that I could take rest with my children, yet I return home when my maid is around and does not travel out. He has not looked it the childrens expense right from time my elder daughter was 1year 4months. He now says he will take care of children but first prove he is the father. Even third child he emotional harasses me saying it is not his child. I am only handling classes from home which is not a regular fixed income. I need justice for my chidren, what do I do without a divorce for this.... or is divorce needed for further. please advice what step I should take, he believes what he is doing is right and blames me that I have made his life miserable and I planned to go back to my mother that is why im doing all this... but in reality I'm facing it all alone in my place. Regards, Mercy.