We want to break Engagement.

I am 25 yr old male and got a govt. job recently . My father's distant friend have a girl 21 yr old ( pursuing master's in scince , didn't completed study yet) , they wanted her to marry me , we didn't knew each other earlier . Earlier her father promised her to not marry or engagement until she complete her studies , but they forced her to come and see me as my parents were looking for a match for me , After our meeting , she denied her parents but they told her how you can deny this way , you should talk to that guy and then decide . The thing is that they (her parents) didn't kept the option to say no and always forced her to keep things in order and forced to marry me . We started talking and she said she has no interest in me and do not want to marry , so we decided to break this thing but her parents started blackmailing her by not taking food , not talking properly and also threatened her to stop her studies, She is serious about studies and requested me to not break so she can continue her studies . I agreed on this and we asked our parents for more time but internally we don't want to marry each other . but our parents think everything is going fine between us and they are preparing for wedding and all. Now we want to break completely without affecting her studies. Please help..