Mental torture, divorce, child custody

Im a housewife married for 7 years and have 2 kids. I have been living with my husband and in laws for past 5 yrs. Before that I was working for 2 yrs and we had stayed in different city. My husband has lost his job during recession and we had stayed in my house under my parents expense for 1.5 years. During this time, husband's brother marriage was finalised and I helped husband with my savings which he gave to his dad. My parents paid money to get a job for husband and we moved to chennai. After we moved to in laws house, I and my kids were subjected to stark partiality with my co sister and her kids enjoying benefits and goodwill. Again my FIL demanded money from husband which my parents gave. I was also subjected to unwilling sex and related mental torture when I refused sex. He badmouthed me and my parents. I want to know • what all cases can be pressed against my husband and in laws? • what is the evidence required to support it. • Are these enough to get a divorce smoothly? • I undoubtedly need custody of my kids. What's the probability of that? Have given the quite detailed post to state the situation and understand my position. Hoping for a good clear reply Thanks