Can a government employee be blackmailed over a contract execution?

Sir, I am a government teacher, and my father is a contractor. My father got a contract, but due to health issues, he is unable to execute it. He asked me to either execute the work or give it to someone on sublet. I gave it to someone, but he failed to execute the work on time, resulting in only 70% of the payments being approved. Now, he is blackmailing me and filing a complaint, claiming that as a government employee, I had no authority to interfere. I gave him the work during our winter vacation and also managed the materials, including cement, aggregate, and labor charges. There was no formal contract or letter with him; it was all verbal with the condition to cut 18% GST for materials or labor used, and pay the commission.