Relationship (though I never agreed) break up and threat.

I know a girl since July. We used to like each other though I never told her"I love u" or any false commitments. One day we were little drunk had sex. She said many times she did because she loves me. But somehow things are not working. She is blackmailing me to come to my home with our intimate picture which I didn't know even existed. Also she wants nursing admission in Bangalore. She told me she will tell no one if I pay her 1.5 lakh for admission which she will return after her job. I denied and she+her mother is blackmailing me, calling me many times, coming to my home, saying I will be forced to marry her,they will take steps. What should I do? Please suggest sir.