Please, make time if only once in the week to do something you like, or nothing at all, if rest is what you chiefly need. And with all you are dealing with, I bet you need time to turn off the phone, put your feet up and read a book or watch your favourite TV programme or film, or go for a walk.
Grieving is a process along a rough and bumpy road, most of the time. What helps me, might not help you, but I allow myself a limited amount of time to be really sad, cry, etc. and then I try to start doing something else. I know it sounds odd, crying for twenty minutes by the clock, then getting on with some boring chore, but it got me through the days and months after my sister's death, which up to now was the worst bereavement I have suffered.
Keep us posted about your grandchildren, it's worrying to think of seriously ill children, so we will all be thinking of you and them.