mental and physical harassment

I met a girl on a matrimonial website 2yrs back. I liked her, loved and proposed her for marriage. she agreed and said if she her parent do not agree she wont marry anyone but will marry only me. I got emotionally attached. In past 2yrs we met 3 times (2 times we had physical relation).Now suddenly 20 days back she said she doesn't want to marry me and getting married to boy of his family choice. But after probing she said she getting married to one of his old friend who i knew about. Now I am totally broken mentally and physically. I am in too much stress. She even threatened me that if i tried to contact her she will commit suicide and blame for for this. Kindly help. I really wanna marry her only, if not what all legal rights I have to take against her for my harrassment. pls help someone.