Prooving Hindu marriage in court

I was in livein reationship with a girl,I never told her that I will marry you.my engagement was placed on 24 th May 21 with an another girl.on 25 th she approached to police to marry me ,police called me at police station, police td me either do marry to this girl or we will book you under section 376 ipc ,under police pressure I was married to this girl in the temple which was located in the police station,there was no priest,no agni,no havan kund ,no Hindu rituals performed,only they give me a mangal sutra ,sindoor or mala.i denied not to marry,they scarred me.they click some photos ,made video and told me that now you are husband and wife.after 5 days of this marriage girl demanded me 10 lakh rs.when I denied she ran away and booked me and my family under section(498a,323,506,3/4 ipc).now what I will do,is this marriage is legal ,there is no any marriage certificate,no invitation card.how I will protect myself and my family from this false FIR.and how will prove in the court that marriage was not legal.plz help me .