False rape case

I work in an office where one of my client aggrieved that his application was rejected and that of his business rival was approved, filed a false rape case against me through his live-in female partner. The lady filed the FIR in August 2016 alleging rape by the business rival since 2010 and then continuous rape by the business rival using threat that he will upload her obscene pictures. My name is not mentioned in the FIR. In the FIR, the lady mentioned one of the date for rape as February and March 2012. In the statement before the magistrate the next day, she mentioned that I had raped her on these two dates in 2012. The truth is that I was in a different office in 2012 and had no connection with the person against whom FIR has been filed in 2012. I have never ever met the lady or spoken to her in person or over telephone. I thought the police will discharge me but now they have filed a chargesheet against me and the case is going to go to session court. I am totally shattered, how should I defend myself?