Taken money on interest

I have taken a loan in December 2016 from a colleague in my office we worked in the same team at a MNC in Hyderabad. He gave me 2 lakh rupees on 14% interest, 7% per lakh, keeping all my original educational certificates, he gave me in cash and instead my payments also should be cash only. Sometimes due to shortage of cash I have transferred 55,000 online, I have paid 14,000 every month for 2 years in cash a total amount of - (3,36,000 + 55,000 = 3,91,000 INR) After which I told him I can’t pay interest any more and requested him or a settlement. After 4 years now he is threatening me to pay a huge amount or else he will not give my original certificates and send people at home for collecting. He has threatened of hitting me as well. His name is Amit Kumar Mohanty and he lives in Hyderabad and is currently working at Amazon and continues to lend money to people on high interest and threatens people by keeping all their educational certificates. I really don’t know what to do.. please help me with the right steps that I need to take to come out of this situation..