My ex girlfriend is accusing me of her marriage getting canceled

Hello, I have been in a relationship with a girl for three years. In June 2015, we had a big fight following which we broke up. It was not the first time we have broken up. Prior to this, we have broken up but always reconciled. This time, within 15 days of our breakup, she messaged me telling that her marriage is fixed. She told me that they have done roka. I tried to convience her for not go ahead with the marriage, because she was also not happy with marriage and she has taken this decision in hurry...In July, her engagement took place. But even after that...we continued to talk...sometimes I talk first...sometimes she does. I tried to convince her many times. But she was too afraid.. Now..in October, I met with her for the last time before going abroad. I told her that this is the last time we are meeting or talking. And I gave her the choice that if she ever want to come back to me, just message me. Otherwise, never message. She obliged to it and we parted on a happy note. We never spoke after that..neither I messaged her not she as we have decided. On December 9, I received a message from her that says, " Mujhe aapki Bahut yad aa rahi hai...kash me past me Jake sab Kuch change kar sakti". I was very angry and I told her that if she doesn't have coueage, she should not speak at all. Thats all...that's what I said... Now after one day, I receive another message from her that says..." I love my fiance...Thank you". Now...on 14 th December, I receive a call from her father's phone...in which they were accusing me of sending a letter to her fiance's home in which someone has written some things...this letter was unnamed. Nothing related to our past was written in it...just some things..like I can't live without her etc. I never wrote such letter nor I have ever thought of doing something crazy like this. I didn't write that letter. Now, unfortunately...her marriage got cancelled. They are accusing me for it. They are blaming me for this. Because I kept talking to her even after her engagement. But they are over looking the fact that she was the one who was talking. Even after all this, I talked to my mom. She said that she is ready to talk to her parents and get to a solution. Her father first asked whether I would marry her...he asked me first..I didn't initiate this topic. I told him that I will have to talk to my parents which I did. And mom was ready to talk. When I told them that my mom was ready to talk...they said we don't want to marry our daughter to you. Even she said she doesn't want to marry. so I said..Ok then. Leave it. I wanted to solve the problem. But instead of solving the problem, they were threatening me. They even threatened to kill me. They told me that they will lodge a police complain against me and make my life a living hell. Sir..my question is...what wrong I have done?..I have always shown respect for that girl and to get family. I have even introduced her to my family and announced that I am going to marry her. My parents were ready for the marriage. they don't have any objection for this..almost my complete family knows about relation. I told her number of times to tell somebody at home..her brother or her cousin. But she never told any body. I only put one condition that I will marry her once my real elder brother gets married. Also...if she would have told me that her parents were searching for a boy for her, I would have changed this condition. Because, it was urgent. But she told me after her parents said yes to the boy..She accepted so many times that she said yes in her ego. Now..what should I do to protect myself and my family? her marriage was scheduled on 16 Jan and I receive her missing me message on 9 Dec. PS: I am a Maharashtrian and she is Jain.