Regarding debt

Hi Advocates, Please help me with the below queries. 1.My dad had taken some loan from a Chartered account of some bank. He was paying interests regularly for 16 years. My mother nor me were not aware of this till last year.Since he couldn't pay money he reached out us to ask for it. 2.He is 65 now. And unable to work. So he is not able to pay loan or interests. I am the only daughter to him. Money lender is now torturing me and my mom to pay the money with interest. 3.We do not have any proofs of the interests paid. But he has made note of all money given and interests taken. My dad has signed that copy which is with him. 4.He has taken blank cheque and some agreements from my dad which I do not know exactly. He is telling he will go to court and police for help. 5. I am married since 3 years. He is trying to find out me and torture me for the money. Mean while he is constantly going home and blackmailing my mother for money. Actually loan amount was some 5 to 10 lakhs. Interest paid was 42 lakhs till now. I am not getting what precautions to take. What only we both women can do. Please Please suggest me the way out for it. How to resolve? We do not know whether he has license for lending money or not. Hoping for the favorable reply.