As a fellow Fibro sufferer I can understand how you are feeling, but hopefully your daughter/son will explain to their children that sometimes their granny is not well enough to look after them and that it can happen quite suddenly. You could always write them a simple letter saying how sorry you were to miss out on this sleepover, but you can't wait to be well enough to do something similar again with them. I treasure every minute I spend with my grandkids and am sure you do, but we can't beat ourselves up when things like this happen as putting yourself under stress will make your illness worse. Sending gentle hugs your way xx
Things that (sometimes unreasonably) get on your nerves...hopefully lighthearted

don't.