Seller Paid Free Shipping / International

So this might be a dumb question but I just recently ran into this issue.

I had Free Shipping on some items using USPS Med Flat Rate box. I had sent offers to interested buyers and one messaged me (so thankful) asking to verify shipping. He lived in Canada and the shipping would have cost me ~$164 on a $120 sale lol
I thanked him for asking first and then went and adjusted those listing to buyer paid shipping until I can figure it out.

The long story short-
Is there a way to turn off International Shipping or How do people do the free shipping if someone from overseas buys the item?

I honestly didn’t even consider the items shipping cost internationally when listing. I’d like to go back to the free shipping but I’m not afraid someone will buy it and the shipping will cost me more than the item list for (it weighs 30+ lbs btw)

Thanks in advance.