Threatening police FIR for irregular payment

In 2019 client lost 2 lakh for my fault in Stock mkt.That time he threatened me to sue and I myself promised to pay 5k every month to compensate. Till date paid 13 payment. I lost my job thats why could not pay him since 3 months and requestd him to give 2-3 months time. He is not listening and threatening me with FIR agaist me.Im always willing to pay. But he use Police FIR to recover his money all the time. Im mentality harrased & frightened due to his FIR threat. What should I do. Im paying and moreover when faild on genuine ground he always threats me. Pl help.