Interesting that you used to do TEFL. I have a TESOL qualification which is basically the same thing. There are quite a lot of English teachers here. A lot of people never seem to learn the language even though they spent 10 years or so studying it. I guess without real motivation it's a waste of time.
Part of my heart is in Canada, but part is also in Korea. I guess it's similar to having two family members or being from mixed heritage/ancestry. I guess if they fought a war, I would have to choose one or the other, but such an event seems unlikely.
I hear you my friend and it will indeed turn out to be a difficult decision for you. Let's hope that it will never happen as I don't think that there is bad blood between the two countries. More of a worry is North Korea methinks. But I stay away from politics and rather try to live a life of peace.
Blessings!