Send him email back, tell him that you'll wait for him and his attorney to show. Tell him, that he is better to hire a million dollar attorney because if not, he will not get his $20 back.... lol....
If everything you are saying is true, I agree the guy sounds like an idiot. I hate to say this, but, you are in India. Unless he can make trouble with your Pay Pal account, I wouldn't worry about it. How is he going to sue you in India? Unfortunately my answer to you is also why I don't do business with people in India. If the situation were reversed and you did a crappy job...equally, there is still no recourse. It works both ways.