Permissibility of disowning a child in Islam

i have married a man and my parents are not happy with the union, as such my father has disowned me from his will. furthermore, he wants me to pay him back the sum of about R600000, which he says is my debt to him for having looked after me and paying school and university fees for me etc.
i would like to knw
a) is disowning your child allowed in Islam?
b) is he correct in asking me to pay him back the money, and am i required, under Islamic law, to pay him?