Leaving a relationship

Hello Sir/ Mam. Good Morning ! I have a query for which I seek advice. I will be very very honest in describing every detail. I was in a relationship with a girl for 3 years. Her name is Hemnandini Mehta She works in same office as mine and we share the same birthdate but, she is 4 years elder to me. 2011 We interacted during our small get togethers and soon, we started to like each other and then, we started getting along well. She shared details about her family in which she was having lot of problems. Her parents are no more, she has two brothers and lives in Moti nagar with her elder unmarried bua. The elder brother loved a girl in their neighborhood and he fought a lot within their family to marry that girl. At last, he married her happily. Her younger brother is un educated. Her bua with whom they live in Moti nagar, she takes care of the household as the parents do. There is one more bua ji who lives in Rotterdam, Netherlands and is an NRI. On and off, she needed support in her family matters and I supported her. Like going to lawyers to seek advice about her father’s will, helping her go to Punjab where her ancestral property is there and so on… Since I had feelings for her, I admired her and kept requesting her if she likes me, let us get engaged or married & for that, she said she would have to talk with her bua and then, proposal would happen. But, she kept on saying that she needs to solve her family matters before talking with her family about me. I agreed and waited for 3 years and that never happened ! Meanwhile, I talked with my family about Nandini and they also were not comfortable marrying a girl who is elder to me, not healthy and is outside our clan. 2014 Then, once she was chatting with one of her friends online and I found out that she met her Ex-boyfriend one night without my knowledge. And she was cheating on me. I asked her the truth and she confessed yes, she met her that night. Next time again, I found her flirting online with a astrologer guy called Sai Satyam. And I could accept anything and would have fought for her but, when I found that she is cheating me out of my true feelings, I decided to move on from her and I conveyed to her that I am not ready to stay in any sort of relationship with her and I would move on. I requested her also to move on and think of herself without me from now on. She messaged me “Fuck off from my life”! and I got a confirmation that it is all over. We stopped talking on phone for long hours, stopped exchanging messages etc. And then, I started focusing on my professional and personal life. I told my parents that please start looking for a girl of your choice and I started to focus on my professional career. And now, some years passed. I met some girls during the process and there was one girl whom I liked and wanted to settle down with her. She was Divya Singhal, my wife ! The thing I love about her is her simplicity in thoughts and wonderful understanding level. But, she wanted to take her time and think about me as a life partner. 2015 Then, I was selected to go to Japan for one year as a part of my professional training. Nandini wanted to see me off at the airport and she came to wish me best of luck. I had no hard feelings for her and told her once again, please focus on mending your life in this one year and think of settling down since we do not have a future together anyways. And during that time, a matrimonial proposal came up from Divya singhal’s family and our families agreed. We started to chat and exchange mails and means…….all sort of communication started happening and a flower started blooming ! 2016 All of a sudden, mails starting coming from Nandini that she wants a come back and would do anything to settle down with me. She mentioned she doesn’t care about anything else right now except coming back to my life. I told her very clearly that two years ago, we have ended everything and now, I am settling down with another person whom I have committed, so, it is not possible for me to breakup from there and think about Nandini. I told her repeatedly through mails that when I do not want to be with her, then there is no point chasing me. Instead, she should look after her professional and personal life but, all that….without me. But, she keeps threatening me that she would give her life and commit suicide if I do not marry her. Query- I feel that I am being harassed mentally and threatened through emails that she can commit suicide if I do not marry her. When we do not love a person, the best thing we can do is to communicate very clearly that we would like to step out of the relationship and end it healthy and peacefully. When two families do not agree to an alliance, it is no point taking it forward. But, I guess this girl Nandini has lost her mind and wants to commit suicide and blame me for causing her death. I do not know what to do? Should I go to a police station and lodge a complaint that she is threatening me with suicide and I must clear that I am not responsible for it. OR I should talk with her family members and persuade them to leave the matter. Please guide.