sale agreement validity

Dear sirs, Iam living in mumbai, I entered into a an unregistered sales agreement for my land in madikeri, karnataka. Since its an inaccessible land parcel. I sold the land with a meagre amount assuming that the purchaser will clear all hurdles and the purchser himself put one month time period to complete the registration and i insisted that the purchsser make all neccessary registrwtion arrangements and inform me well in time and gave all original documents and then make the registration as iam an outside person. But he didnt register and i was offered higher rate and since he asked sometime i agreed to wait and said no to prospective buyers, But after an year he sent a notice to register the property and by the time few other ppl came and asked for property three times value.so I sent a reply notice stating that his time period is over but iam willing to register by asking for higher price but only .5 times and gave a time of one month as . Still he doesn't reply and after a year again he sent a notice saying he doesn't want land as he doesn't agree to my new conditions citing new forest regulations and is asking the money back. Now I'm stuck with the property with no buyer and he has now full control of the property as he now has the original documents. He sent a notice saying he will attach my property if I don't pay with 2 years interest. Is it my fault the purchaser failed twice to honor the one month time and also deprived me of my chance to sell the property at higher rate. I was showing humanitarian side by giving him more time to register....pls give your valuable opinions. Thank you