Threatening by girl for not marrying her

Good morning , I live in Lucknow and the girl and her family lives in delhi. 2 years ago we met through matrimonial website and later I along with my family went to see her to delhi.we told them that we will talk about marriage after Feb 2015 when my elder brother will get married. After February 2015 our family had called their family on phone and asked them how will they perform all the custom of marriage... We asked them about the budget of marriage, we also asked for car which they denied and they said they can not give as they have not so much money.. Then we said OK don't give car , just give 5 lakh rupee cash. Her father said they can give only 1 lakh rupee.. So we decided to not to continue this proposal as her father once gets agree then disagree like we ended this proposal. Mean while I and girl kept on talking on phone to keep these things on main line for this I went to delhi and met her in a hotel in a roomin August 2015. Where I told her that I will try to talk my family regarding this. In that private moment we came close and did a physical love and oral sex but WE DID NOT DO INTERCOURSE. later when I came back to my city and talked to my family, then my family said that its not good to marry in that family as their rude behaviour and compatibility issues. So I said NO to girl for marriage. Now in february 2016 her father and she herself is calling my sister my Jija ji my mom and threatening all of them that your child has played with my daughters life and body and raped her in hotel and they have said that they will not leave me and will take a legal action against me and my family.. Please help me what should I do as my marriage is already fixed somewhere else and roka (custom of fixing the marriage by giving some money as Shagun) has been done.. Please help me.