How to deal with undue force for marriage

sir i have girlfriend met 4 month ago, same cast she initially told me she is graduate and born of 1992 , i asked her to arrange marriage if she want, her parents met my family everything was fine that parents ask for educational documents and come to know that she is doing 12th and born of 1986, due to these my parents refused and our relationship end,10 days later she called me to stay as friend we went in physical relationship accidentally and we go to hospital for chech her pregnancy she was not pregnant. she have pictures of us kissing in garden. now she is forcing me to marry and threating me for medical documents, pictures and dowry case. she want to marry me. what should i do.? hindu