He doesn't have much of a case if there is nothing in writing from you indicating that you accepted these things as loans and intended to repay him.
Your father's friend was extremely kind and generous. Clearly he has regrets. What has changed? Perhaps he and your father had a falling out? Perhaps he feelx unappreciated by you? Has he fallen on hard financial times? Did he expect you to respond romantically? Maybe that is what really needs to be addressed. I would not admit or act that these are anything other than gifts but perhaps hurt feelings can smoothed over.
Absent a written agreement, any disputes must be either resolved or a suit initiated wihin three years of the, in this case, breach of the supposed contract. It may be too late for him to proceed but that will depend on facts as to when the purported breach ccurred.
A gift by definition does not require repayment. I would carefully review anything you have in writting such as emails, letters, thank you cards, texts, ecetera as those can be evidence, one way or another as to whether these were gifts or not. I also would be very careful about anything you write about this sitution.
I assume Day's friend means dad's friend. Without something in writing signed by you evidencing that these were loans, the court will consider them gifts, but you still need to defend against the actions.
If you'd like to discuss, please feel free to call. Jeff Gold Gold, Benes, LLP 1854 Bellmore Ave Bellmore, NY 11710 Telephone -516.512.6333 Email - Jgold@goldbenes.com