Depends..
If you borrowed money from him, then it'd be better to pay back, or
he paid a huge sum of money for you, like a few thousands, pay him
back too..
If he's asking for the money he spent on you, like on dates,
presents, small bills, etc, those that he willingly paid for you,
then don't bother with jerks like him.. send him a bill for the
TIME you spent on him.