Catherine,
How are you doing today? You've received some wonderful advice here. May your 'blue funk' move along soon.
I have to share a story about our first exchange students. First off, a little background information, our three daughters were all adopted from Korea. When our girls were in high school we had a Japanese exchange student for just a month. When it came time for her to go home there the whole family was crying and sobbing. We were a mess. Once the bus pulled out of the parking lot my husband turned to me and said, "We've never had to give one back before!" He had said exactly what we were all feeling! We always want to keep them forever! So go ahead and have a good cry when the exchange students have to go home.
The other idea I've had while reading all of the posts is to be sure to get out into the sunshine. I find that if I have had too many days inside I'll get to feeling blue and it's amazing what a little sunshine will do, even if it's only 10 minutes or so.
Also, please know that there are many, many prayers being said for your granddaughter. It helps to know you are not alone and we are all here with you!
Take care of you!