Cancellation of advance paid agreement for an immovable property

Dear Sir, I am Madhu from Bangalore. Sir I have entered into an agreement to sell my property which is a plot for a consideration of Rs.22,00,000, and entered in to an agreement with a purchaser. The purchaser paid me an advance of 5,00,000 and he only executed the agreement. The property is a revenue property and it is difficult to get site purchase or site purchase cum construction loan from any financial institutions. Also I have informed him very clearly that whatever the documents I have will be the final and no further documents will be provided by me and if at all he requires any further documents the purchaser himself will arrange. Knowing all these, he agreed and said he will be purchasing as a cash purchase and entered in to an agreement on 24th February 2015 (not registered) mentioning in that the sale will be concluded within a period of 2 months from the date of agreement. Also mentioned as if in case the purchaser cannot fulfil his commitment with in this period the advance amount paid will be withheld by the seller and if the seller is not agreeing to sell the property, then the seller will have to pay the purchaser double the advance money. After 10 days he said I want to take loan as I am facing some financial problems. I agreed since we had 2 months time to execute the purchase. He then in several occasions he met me and asked for several documents which I categorically said I do not have and I cannot furnish and also remained him that you have agreed for document collection by yourself. Now he is saying that since he is not getting any loan or financial assistance from bank or NBFC he is withdrawing himself from the contract or agreement. And he is demanding the advance amount in full to be repaid to him. Now as I have invested some amount in that advance money I am not in a position to give him back. And also as he mentioned in the agreement if the cancellation from the purchaser the advance amount can be forfeited by the seller I as a seller do not want to return his money. The one more reason for my decision is in between he contacted some of the real estate brokers without my permission or knowhow he initiated the sale of my property for a consideration which will benefiting him by keeping a margin. And keeping me in dark about the proceedings and many times he said only lies. He said he is coming with actual party who intends to purchase the site and he came with 2 brokers whom I know and they are dealing the same with one or more brokers outside. He said he is going to purchase on full cash and he went to take loan. Kindly suggest me how to go about this situation as I feel I am getting cheated and without my knowledge on my property some one is making un law full money. I want to cancel the agreement for these above mentioned reasons. If I can get your reply to mail id which is m.tv@rediffmail.com, I will be more happy. Thanking you With Regards Madhu.