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 Legally  you cant file case of cheating and breach of trust  against her . If she because of her parent pressures file complaint against u , u r in trouble . Marriage is not a pressure game .

write a letter to registrar stating that the girl is not feeling well and take some more time and convince her father to get married to her daughter being a last chance to conivince her if you succeed then okay or else cancel the marriage by giving a formal letter stating that girl is not intrested in marriage and cancel and do your work if girl is not turning to you 

sit tight in home.  The girl will not support you iof you write anything.