Cyber Harassment

A guy (occupation: doctor) had sent me money (3000 INR) for shopping 3 years ago just to impress me. Despite of my refusal twice, he didn't take it back. I wasn't impressed by him though. He gave up stating to just be friends. I agreed. After 2 years he got in touch with me again and started flirting. I did the same Because I was single at that time. The texts went to sexting and he had sent me his private part's picture. I wasn't opposing at that time but I felt uncomfortable by this very thought the next day so I blocked him considering I don't want to do anything with this guy anymore it's shameful enough for me. The very next month I got a call from a girl claiming to be his girlfriend and they were dating from the past years. I told her that it isn't my fault that your bf talked to me it's his. Plus the conversation you are having with me should be with him. I was single and I had no idea of him being in a relationship. So you should talk to him. After that incident I got a msg on phone pay from the guy stating he wants to have his money back. I don't have anything to give him now. How can he expect me to give him back the money he gave me to shop that too years ago? I blocked him. And today after a year he again msged me on my other Sim card saying he'll report me to cyber crime. So Iam writing this cause it's been so long of his on and off harassment. I got nothing to do with this guy. I have no interest in either meeting chatting or having any kind of communication with this person. Despite of my refusal he keeps coming back. Hence I want someone to suggest me what can I do to stop this because I don't have any money to give back to him that too after 3 years.