Blackmailing

I meet a girl in December 2019 via dating app. On 1st meeting we talk about what can be future of us and we conclude that there is nothing like future or marriage. I refuse for any relationship as i am looking for life partner. We she insist for the relationship and say that lets see.. there is no force of marriage form her side. After 6 months of relationship i feel that she is a desperate girl. She start forcing me for marriage and taunting me. But still i decide to take her side and support her. We told about our relationship at home. After that my family get ready for marriage but his marriage asked for time.. they take around 5 month and say no to my family. After that i ask for breakup. But she emotional blackmail me and torture me. I say that i am not running or using her.. i am ready for court marriage. i take 3 time date but she refuse at last moment. I family ask for marriage with another girl, i ask her that if her family can contact to my family but she refuse and say that.. she will do marriage as per her family and i am free to marry. Now i got engaged with someone else..now she is threatening me ,blackmail me..that she will do let happen my marriage and pressing to cancel my marriage. Please tell me what to do..