my son did not qualify for any school grants etc.he was 21yrs at that time.i took a parents plus loan for his tuition to cooking school in nyc.approx. $67k.we made a verbal agreement that he would pay the loan back and i would help him pay it back.we made no fixed payment agreements at that time.we would decide how much he paid when he graduated.he graduated and now refuses to talk to me and says he is not paying the loan back because it is in my name only.can i hold him to the verbal agreement?