AITA if I don’t pay my uncle back?

I (F23) have recently graduated from university and got my first job. The job is a minimum wage job and I don’t have much spare money left after paying my expenses.

Since I was born, my dad never had a job. My dad didn’t work since he was in his 30s. He doesn’t have any physical or mental disability but he just doesn’t work despite being highly educated with a Masters degree. Without working, my dad doesn’t have much money himself so since I was young, my mom paid most of the household expenses.

However, in my late teens, my dad told me that my uncle decided to contribute to my education and allowance. My dad never told me that it was a loan from my uncle and the money from my uncle was transferred to my dad’s bank account and then he use it on my education and allowance. I was happy back then and thought that the money from my uncle was a gift. When I was in university, my dad told me to fully focus on my studies and not get a job. He said my uncle willingly gives me monthly allowance and told me to fully focus on my studies instead of working part time. I never worked during university (I know this is a mistake on my part).

Recently, my uncle suddenly called me on the phone and demanded that I need to pay back to him the money he spent on me throughout the years which amounted to around $100,000. He was insisting that I have to pay him back monthly since I have a job. But I find it very difficult to pay him back such a large amount of money because I have my future plans of getting married and having kids which I need to save up for. And it has been very difficult for me to find a job with decent income. Most importantly, I was never aware that the money was a loan.

I told my dad about what my uncle told me and now my dad said I have to pay back my uncle. There is no written loan agreement and I have never personally agreed to getting a loan. My uncle is also quite wealthy, he lives in an expensive house and according to my dad, he has a few million dollars in his savings. However, I feel morally conflicted as I have benefited from my uncle’s money and I feel that I might be morally obligated to pay him back. But if I pay him back, that means I will struggle financially and may not be able to achieve the goals I want to achieve in my future. Whereas my uncle is wealthy, he can live comfortably and he doesn’t need to worry about money, unlike me.

AITA if I don’t pay my uncle back?

EDIT: I did call my uncle to thank him when he started giving the money. However my uncle never mentioned that it was a loan. During the past year, I also called my uncle occasionally to check on him when he was ill. Again, he never mentioned that the money was a loan, until recently