How can I get money back from friend to whom I have given money?

I was giving money as a help to one of my friend in London. We were living in the same room and he was like family friend. I had been paying his rent for nearly 3-4 years in London. And also provide help by paying his college fees and other financial need. The total amount can be at least of Rs. 5,00,000. As he was very close friend, I didn't bother to keep all the bank statement but he has kept all the bank statement (from bank in London) for years. I was seeing this money as my saving of hard work which I have earned abroad. While in London, I did not even bother to keep record of this due amount. I was transferring all his money with blind faith in him. We both are now back in India for 3 years. I have been asking my money back for last 3 years and he has not paid single rupee so far. He is now denying the fact he owes me Rs. 5,00,000 which he thinks is too much. He was contentiously claiming that he has bank statement (of london bank) from which we can figure out exact amount. We both agreed at many points where we decided to sit down and go through bank statement to fix owes amount but he is contentiously denying and neglecting this situation. I have proof and screenshot where I have made nearly 40-50 calls in a day to get his reply so we can meet, But everytime I got a written message from him saying he is in meeting. I have sent him 100s of whats app messages and text messages in decent language requesting him to coordinate in this case so we can come up with fix amount. And this situation has been going for last 6 months. At some point, in the text messages, he seems agreeing that he owes me some money. But he tactfully denying to comment on exact amount in written text. And he never receives my calls. As he was not replying to my calls, I have tried to get this matter sorted through his wife. I had communicated with her on whatss app. But even she has chosen not to reply to me. I have refrained myself from any wrong doing or bad attitude on any written chat or call. But I had last meeting with him on couple of days back where he was saying that he can arrange some money from his sister to give me back. In the conversation somewhere, i have said that "I had done enough Gandhigiri in resolving this case but I have to take some strict action (legal or illegal) to fetch money from you." And he has taken this sentence as I am threatening him and will hit him and his family. In the same conversation, he has denied that I don't have to take Rs 5,00,000 from him and that amount is merely Rs. 25 -30,000 which is absolutely not. He also said that there is no proof that I have given him money to support his family in India. He literally started being mean. Because of his behaviour I have lost control and started using ill words and threatened him to hit him. Most importantly, I have recorded this whole conversation and I believe he has surely recorded this whole conversation as well and we both have audio recording of this conversation. So my question is: 1) can I sue him as I have written proof as whats app message where he seems agreeing that i have to take money from him? But he is denying the amount of Rs 5,00,000 neither he is providing any amount which he may think I have to take from him. 2) what if he goes legal and file FIR and court case against me saying that i have threaten him to hit him for money which he never taken from me? Because all the transaction has happened abroad. 3) what are the chances of me can get money from him? How can i claim money from him?(legally or illegally) 4) I have loads of proof where I have called him 40-50 times but he never receives my calls, I have proof that I have tried everything decently to sort out this matter but he is not interested to resolve this matter because there is no proof (as per indian legal system) that I have given him or his family money. Can i simply says that my family (in india) gave money to his family in india? And this matter is completely different than what he owes me with the matter in London? But at the same time there is written proof supporting the fact that this matter is linked to London life where money transactions happened. But my intention to support his family back in india. Please please help to sort out this matter. This is the only money I have saved for my life and he is not giving me back turning so mean that I can not even digest the fact that such a nice friend become so mean. It is complete injustice.