Harassment by a friend who had landed money

A very close friend of my husband approached us to lend money when he came to know we were arranging money to buy a property.He said to take the money and pay the interest monthly . Monthly interest were paid to him regularly since 2019 to till date . During last yr covid lockdown we faced a financial troubles as my husbands business was zero . Seeing us struggling he started demanding money . My husband has literally begged him but he has continued harassment and threatening to involve our family in this.He has defamed my husband by circulating mails to family n friends, FB post and txt in messenger, what's app group txt. His harassment is going beyond limit .we are getting calls and messages from him at odd hours in midnight. And he has arranged rowdy also to threaten us.when we tried talking to him directly he is not ready to speak and just keep running away with lame excuses. He is threatening to complain to IG now. We are still facing financial trouble , but still we have told we will return his money within a month but still he continues to harass us. We have take only 10 lacs from him but he says he has opened a OD accountn have paid us so we have to pay him nearly 37 lacs to him now. The interest of 16000 paid on 2019 was increased to 40000 monthly from 2020 . But he says he can't consider tat money and we have to pay 37 lacs. We are going through a lot of mental harassment because of him. Someone kindly suggest what to do.