Rental terms

Dear Sir, with the intention of letting out my apartment I showed it to a prospective tenant who wanted it for himself and his friend and took rs 10000/- as a token advance. In my mail to him I mentioned the terms and I mentioned the agreement starting date as june 1st to which he had agreed. I proceeded with the painting and handed over the key to him on the 5th so that he could move in on the 7th as he wanted. But on the 6th he backtracked and cited the reason that as his friend had got transferred he could not bear the entire rent by himself. I have agreed to refund around 4500/- after deducting the assumed rent for 7 days. But he is not agreeing and he has completely twisted the whole thing by saying that I had not finished the interiors (which is completely untrue and was not mentioned as part of the terms) as a result of which he was not moving and wants the entire refund of 10000 otherwise threatening to approach the court with a totally fabricated version. unfortunately other than emails shared I do not have any other evidence. The proper rental agreement was not done and all communication is only via mail. Am I liable to pay the entire amount to him and is what he is claiming legally tenable. It is a very small amount to be disputed in court but the person concerned seems to be hellbent on making it a legal issue. Kindly advise