Registered Marriage, witness being falsely implicated

Dear Sir, Myself and my friend signed as witness in a registered marriage of our class mate. He is a engineer (30 yrs) and lady is a software engineer (27 years) both working in a MNC. This happened in 2013. Both were physically present at registrar office during marriage and had visited a temple later on Both had requested us to be their witness. Since we know them from 6 years, we agreed and signed it. Things turned sour between the couple and she had filed a complaint that marriage is fake, she is not aware and witnessess forced her into it (Pressure from parents, inter-caste marriage) We were called for enquiry by the local police and we provided statement saying that she was fully aware of what was happening and in fact she requested us to be her witness. Mean while after marriage she had attended several weddings happily as a couple, including my marriage. Meanwhile We had provided the video footage of my marriage where they attended as a happy couple to the police and one photo clicked at the registrar's office. Further my friend has phone conversations recording that she is interested and fully aware of court marriage. Kindly advice how to safe guard ourselves as witnessess