Need Help Regarding Debt

Dear Members, i have a query regarding my debt which i had taken 5 year ago.. in 2008 i had takan 20k from money lender for 120 days on daily payment basis i.e. 200 everyday.. i had given him blank cheque (bank account closed in 2009 bcoz i had student account )and signed stamp paper.. i paid him regularly for 1 month later i shifted to other place.. after that no communication with him for 2 years .. in between i started working and i again called him and started paying monthly.. till now i paid him 20k in cash during year 2012 + 6k in 2009... but now he is asking me 25k more + if i delay he'll charge interest on 25k and force me to pay along with interest.. he is saying he suffred loss due to me.. i m ready to give him 5000 more.. but beyond that i m not capable to pay him.. just want to know legal consequences of stamp paper and if he deposits cheque(account already clsed by bank bcoz bank asked 5k to convert zero balance student account into saving account i didnt accept offer). and also advice what is the last amount i should give him for settlement.. plz advice.. thanks in advance...