Is unregistered sale agreement valid?

I signed unregistered sale agreement on 200 stamp paper with token advance of 1 lakh, property value is 90 lakh. Buyer told this draft agreement only for home loan purpose, later proper registered agreement will done. There is no penalty clause in agreement if Seller backs or buyer back from deal and agreement has sign only in last page not all pages and there is no ID proofs mentioned in agreement. Sale agreement mentioned registration needs to done withing 3 months. Now I decided not to sell my property need to preserve for my children .I informed buyer within 3 days after signing unregistered sale agreement that we are not planning to sell now and we can return your advance. But he is not listening forcing for registration and demanding 10 lakhs.I am ready to return his 1 lakh advance with 10% extra also,but he is threatening to take legal action.He brought 15 peoples to make us fear and to do force registration,pls help