Woman blackmailing.

I met a degree classmate after two years in a friend’s marriage two years ago. We talked to each other friendly. She is financially so poor. She told me that due to financial problems she couldn’t go for coaching for the competitive exams. Then I understood her problem , and as a friend I helped her to join in coaching centres and I have been helping her financially since last year. I considered her as a friend and I helped. Now , I am going for an arranged marriage and I used to told her about my marriage matchings and I used to ask some suggestions about the matchings. She also responded like a friend and gave some suggestions. I do not have any thought of love or marrying her and I’ve never seen her in such way. I have never behaved wrongly with her. My marriage is nearing and my family is getting every thing ready for my marriage. But now , she is blackmailing me. She is blackmailing me to marry her. I told her that I do not have any thought of marrying her , I considered her as friend I do not like to marry. She blackmails that she would commit suicide or inform my parents and spoil my life. Every day and every moment she blackmails me through phone calls and mms .But I couldn’t switch off my mobile as it is linked to my career. So please show me the solution to get rid of this problem.