How to defend cheque bounce case?

I got a debt of Rs.3 lakhs from a person on nov'2016. My friend got 2 blank cheques from me , and got money from his relative. I dont know that person directly. I got money from my friend only, and gave interest through him only. Rate is 3% per month. I already gave approximately 1.25 lakhs interest. Now for the past six months i didn't pay the interest , because my financial position became worst. I have account in 2 branches of same bank. The bank asked me to close any account. I closed the account that the cheque was issued. Now the third party ( Friend's realtive) threatens me to file case. I asked him to wait, that i will sell a land and returns the money. But it is difficult to sell the land, because nobody offers a reasonable amount. So it will take some time. He asked for the money immediately. How can I take precautionary steps ,if he files a case. Since I am a government employee , is there any suspension given to me? Please advise. The cheques were given as security only. No agreement has been made? can I file a case for high interest rate asked by him?