A Girlfriend forcing me for marriage

Hi Sir, I met a girl one year ago on matrimony site, when we introduced each other I took her directly to my home so as to show my family whether they like her or not. They did not like and refused to accept.I am a lower middle class boy, 25Yr old, believe and strictly follow my parents suggestions.hence I told that girl that my family and I are opposite to this connection. On the second day she called me and said we can live together as a gf-bf for atleast the time before I or she gets married to another bride/groom. i was a idiot that I thought I should be okay with her..this was my main mistake. Gradually we used to do meet, dinner, movie and sex together. After 6-7 months are spent together she started me asking about marriage. I said we had cleared this already that we won't be marrying each other.she said her decision is now changed and she is in love with me so she can't live without me. Then I started avoiding her and kept her away. But now for last 4 months everyday she calls or texts me and says pls meet, talk to her otherwise she will die. I am really frustrated on this. I know initially I did a silly mistake by accepting the temporary relationship but now she is really behaving like a hell. Can you please suggest a way how to tell her that she should stop saying this and broke up with me. I don't wanna marry her in any situation. Thanks in advance.