Need help, she is blackmailing me ?

I am 26 and she is 26 too, i am in relationship with this girl from past 1.5 year. we had sex 3 time and last time we had done about 2 month back. now in the period of this relationship we had lots of fight (every week), she is mad about me but she dont trust me at all, she fights with on my past, even if my phone get switched off she called me on my dads number, how 1 and half month ago she decided to get married with me , i am so stupid that without even giving a second thought, i talked to my parents and our family meets. there is a disagreement in our families, however my dad said that you should took a time (1-week) and decide and give me answer what should i do. So my gf is not even allowing me to give me that much time and blackmailing me that i ruin your family life and all. and i will tell your parents about sex and all. now after 1 month of time i decided not to merry her by seeing this behavior (i hope i made the right decision), my question is that is she can do anything legally against me, filing rape case etc. Please tell me i am in deep trouble. apart from this i also care for her i want her to move on from me, i always pick her call she always abuse me like anything but i always listen everything she say (against my family against me), as i think she get relaxed after this. Plz help me guyz !! thanks