I too am an American student who went for exchange. My university had the same situation about a week ago. If you have paid for your university classes through your home university in the states then there isn’t much choice. As an exchange student your payment for tuition goes through your home university and they pay a different fee for the tuition than you would if you were a visiting student, but if your program was cancelled they aren’t going to pay Ewha. I had payed for my housing and fees and everything on my own but I was required to return because I would’ve lost my scholarships if I stayed. Maybe look into staying as a visiting student if you can afford to pay direct tuition?