Abusive mother in law, sister in law and husband's relatives

My husband and I are married out of different caste. We both are classmates in M.Tech. Though initially both parents approved later my parents disapproved. We married at the age of 26 and 28 in a registrar office. Initially my in-laws were good, later his daughter got divorced. My MIL and SIL plotted to take-out financial independence by threatening to give his whole salary to them and make me run the family on my income. We disagreed and they started involving relatives to threaten us. My sister in law was divorced by her husband acquitting that she had extra marital affairs. After her filing of divorce, she has started dating couple of random guys and started involving us for her mistakes. I got pregnant recently and SIL,MIL and her relatives are on to us to pull out financially and forcing my husband to divorce me. My husband has been very supportive, father in law is a neutral audience. SIL, MIL and her relatives have threatened me to continue the abuse since I cannot prove or file cases on them. Please advice how to proceed legally. Property share has not been done between my husband and her sister. They're threatening to not to share the property too.