Signing legal document proof stating that there's no relationship with in laws

Married for 3 years. My mother in law and two sister In laws disrespected me, harrassed me for dowry, I stayed away from husband family members. But husband was never pleased about me because he thinks I broke his family. All 3 years he behaved like a stranger to me and never understood the fact that his family is harrasing me. He put a condition to me, to struggle with his family harrassment for 3 years, so that his family will be pleased and their ego geta satisfied. I just sent him mutual consent and he agreed initially. Now he is convincing me for reconciliation, saying that his family stay away from us and does not interfere. But now his family people and my husband put a condition saying, inorder to continue my marital life, I need to sign a legal document stating that I won't have any relationship with his family members. And his family are also ready to sign the same. I want to know, what is the risk factors here? These kind of legal document.will be misused in future? Even after signing, would they trouble me again or harras me? Does these papers are valid? What precautions do I need to take if they insist on signing the paper with these statements?