Girl trying to destroy my family and told lie about her past

I am in the relationship with a girl last one year and parents fixed our marriage and marriage date is decided to be on March 2016. We met couple of times and we already had the physical relationship with mutual consent. Couple of month ago i came to know she broke the engagement with another guy and file a case against him under Sections 450, 376(2)(n) of the IPC, the case is going on . When i asked her about the same she said the boy's family was demanding dowry so she filed a case against her. I trusted on her because her nature was very good so i started supporting her. Now ,I came to know she did hide so many things and truth is completely different what she told me,even she told me section 376 was wrong and she did this because her lawyer asked to do in order to make her case strong. Despite I found she is trying to break my family she speaks lie in every matter and send me the suicidal messages and videos.she started blaming my family and Threatening me to separate with my family. Initially the girl nature was very good and nobody noticed anything wrong even i never thought about breaking this relationship. She made the plan and convinced each member of my family that she is a very good girl even I never ever doubt on her about the same. Last 2 months she was trying to create the dispute among other member of my family actually everyone blindly trusted on her so nobody believe that she was telling lie and after that my family started dividing (she played divide and rule). Couple of days back she mistakenly sent a audio recording and couple of fake whatsapp messages to me stating that my elder brother and elder sister hates me when i clarify to my brother and sister they said they never sent such kind of messages. when i asked her to prove the authenticity of the messages and recording, she panicked and start blackmailing me and sent me the suicidal video in which she was trying to cut her hand with a knife. She also told my sister in law (brother's wife) she will destroy the family after marriage because i have no choice to call-off this marriage because i had the physical relationship with her. Now when my whole family united and clarified all the things than we came to know she is a fraud girl . I am very simple boy could not understand her plan because i was deeply in love with her , even i never say no to this marriage. But i know very well if i married this girl, she will separate me with my family and life time i have to sacrifice because she will blackmail me to do anything like she does now . I and my family completely broken because nobody can understand her game plan . I have kept all the attempt to suicidal videos and messages of her . Please guide me how to save me and my family because she is very clever she knows the legal laws and she kept all the private photos of our relationship. I have one recording of her mother stating that me and my family is very good and her daughter did not do the right thing to my family and she is ready to call of this marriage but the girl refused to do the same and keep sending me the suicidal messages . Please help !!!!