Harassment by my sister in law and her husband over property

Hi, I lost my husband 5+ years ago and my father in law 3 years ago. I have a 5 year old son and I am a working independent woman. However, my sister in law and her husband are not letting me live in peace since the day my father in law died. My mother in law passed away years back so now the legal heirs are just me and my sister in law. We have 2 properties: 1. My husband's house - where currently I am staying with my son. It is a self acquired property in the name of my husband. My sister in law has filed a legal notice to the local registrar's office that the house was purchased using joint funds from the family and that she has a right over it. Please guide me here. 2. Commercial property - Where my husband and father in law used to run their business, it is in the name of my father in law. The papers of the property are in the custody of the bank as my husband took a loan against it to purchase the house. My sister in law doesn't wants to sell the same claiming that I am and my deceased husband have robbed away the family's gold for about 1.5 crore which never existed. 3. Family locker - The locker was in the name of my father in law and my sister in law in either/survivor rule. Neither me, neither my husband could access it alone. After my father in law passed away, my sister in law and her husband convinced me to give them the locker keys and that they would give me my maternal gold. Its been 3 years she has not returned the same to me and I have never thought og going to the court thinking that it is better if this gets settled outside the court. But now my patience is over, there have been numerous cases where my sister in law and her husband have pushed me to sell the house but I did not. They do not want to sell the shop because they say it openly that they wont let me have my share. They claim it to the world that they will destroy me and my son. Today I am here on this platform seeking help so that I can teach them a lesson. How can I obtain my right and file a case against both of them?