Cheating of girl to a boy in love affair

I Navin , age 35 residing in mumbai and Meenal mishra, age 29, residing at Bhandup (E), Mumbai-400042, have been in love relationship since 2010. its been almost 4 and half years. I am belonging to saini caste from haryana which is kshatriya and the girl is mishra from U.P. state which belongs to brahmin. I am well educated, MSc, Mphil. B.ed. I am working as a lecturer in a reputed college in, mumbai. The girl is also educated, M.A. she is working as a clerk in Govt office (khadi Udyog) the parents are opposing the marriage on the grounds that i belong to a lower caste as compared to brahmins. I know her family since last 9 years. The girl has even introduced me to her elder sister 6 months ago and her elder sister did not had any objection to our relationship. The Girl was scared to talk to her parents and did not ever let me to talk regarding our relation to her parents for marriage. Though I have spoken to my parents and obtained their permission. suddenly i came to know her marriage has been fixed to a guy in delhi, that is when i approached the girls parents. the parents are now saying the girl did not tell us when the marriage got fixed. i still requested them to break that arranged marriage and think for me. Her parents thinks i am of low caste. her parents have obtained the permission of daughter by blackmailing her that if u marry the boy our of caste, we will be getting a heart attack. also the father told me on phone that if i let my daughter marry out of caste, none of my realtives will even ask me for water when after retirement i go to my native place. In the same family their son, elder to this girl working as a Major in Army is going for love marriage with a girl fo other caste, even though the parents have agreed to this love marriage after a long period of opposition. the same parents can agree and allow the son to go for love marriage, but when it comes to the daughter there are double standards.The girl has supressed her true wishes in the interest of her parents image in society. Her marriage is fixed to a guy from her caste. Those guy's parents are demanding dowry including a car, the father is still going to marry with such a guy. The girl's parents and even the girl is now denying that we were in a relationship althogh she has sent hundreds n hundreds of messages on mobile, whats app and sent many photographs which normally a girl sents to boy in love relationship. the boy to whom her marriage is fixed is very rich and wealthy guy so now even she is back footing herself in the interest of a wealthy proposal. Today on 1-11-2014 the girls father, Mr.Ramesh Mishra who is also working in Khadi called me and threatened that he wil file a false complaint againt me. later her daughter, Meenal Mishra also called me and abused me and threatened me with filing a false complaint for misbehaving, threatening and all false allegations on me. I am shocked that even she is denying that we have been in a relationship and calling it as a casual friendship! she said to me " that I am a girl and everyone will beleive me what ever i say" After been in relationship for a long time almost 4 to 5 years she has ditched me, deserted me. broken my trust. which is a criminal breach breach of trust. and also to add insult to injury she is now threatening me with a false complaints. the girl and her father both have threatened me with false complaints against me, so in the event they file false complaints against me, what do I do? can u please help me? I am very tensed and mentally disturbed. can i file a complaint againt the girl and father for threatening me? Can i lodge an N.C. in advance so that in the event they file against me, I would have had already informed the police. Thanking You