False cheque case filed – how can I defend myself?

A person blackmailed and extorted me with the help of police officials at the police station. He took three of my cheques and made me sign a false agreement in the presence of the police, claiming that I had asked him to transfer money to a third person's account. However, there was no transaction between us. He transferred the money to the third person's account, but there is no evidence that I received any money. He manipulated the police officials to threaten and force me into signing the agreement. I immediately submitted a stop payment request to the bank for those cheques. Despite this, he sent me a legal notice for cheque bounce and filed a case under Section 138 of the Negotiable Instruments Act. After the incident, I filed a complaint with the Commissioner of Police, but no action was taken. I also filed an application under Section 153(3) CrPC, and the court ordered an investigation. However, the accused police officials filed a revision petition under Section 397 CrPC to challenge the investigation. My question is: How can I defend myself in this false cheque bounce case when I never received any money from him, and no transaction actually took place?