A girl is blackmailing me

Hi , When i was doing my graduation we were in love and i thought it is okay after my graduation she left her hometown in 2014 and i had moved to other city for my job and we rarely used to talk from that time and i also i told her before 2 years that our marriage is not possible when i was young i did not know about things better now i have a vision to see things from Brighter side.. Now i had got an match where i like the girl and even the girl likes me and our both families have mutual understanding and i think i can stay happen with this girl. But just 2 days back i girl come to know that i am getting married and blackmailing me that to marry her or else she will spoil my marriage by telling to my parents and to the girl , however i had informed the situation to my mom and the girl whom i am marring. She is keep on threatening me by sending messages like i have you messages in college days i will surely create problem in between you people during or after marriage. Please suggest how to get rid from her. her only concern is like she i not getting good matches and she want to take that revenge on me. Thanks, Harinath