I do sympathise with you especially if your son has had some issues before living in Australia but hopefully now he is happily settled with a new wife and children he will be fine.
From your perspective though it's devastating. We went through it 7 years ago when our youngest son emigrated to NZ when his wife was pregnant with their first child. She was from there and her family were all there so it didn't really come as a surprise but that didn't make it any easier. I spent several months before they went crying quietly to myself. The week before they left they spent with us and we had days out together and a big family get together for everyone to say goodbye (so sad that's not possible at the moment). It was heartbreaking but actually I think the build up was far worse than when they had actually gone. You get used to it and with so many great ways to communicate now you will be able to talk to your grandchildren. You have the advantage of your GD already knowing you and being close so that bond will remain as she grows.
Soops place of refuge and friends
What decade were your grandparents born?
What do you find yourself avoiding more as you get older?
Desperately sad story of the assisted suicide of a grieving mother

