A girl is threatening me! Please help.

I met a girl on fb ( there was a rishta from her family for me) but we have never met till date. We started talking and she wanted to marry me. I had a breakup then.. I told her everything that I love another girl. She was being supportive and because the girl I loved was not coming back I told her that if it happens that I do an arranged marriage.. I will marry her. But we had not even met. Soon she started seducing me and we had virtual sex on skype and phone calls. I used to feel guilty and I told her everytime that I love my ex gf. After sometime my ex gf came back... and I stopped talking to both of them and finally got back with my ex. This another girl (not my gf) was always into my career and job bcz I earn quite well. She was also talking to other guys before we met for as long as an year amd left them for me. Now she is threatening me that she will commit suicide if I dont talk to her parents for marriage. I dont want to marry her. She is doing all this because she is not getting a guy who earns as much as I do. She is also threatening to lodge a complaint against me and defame me. Please help me.