I'm an expert.
The kids will play it either way if they are so inclined.
Damn if you do or you don't.
So do what you think is right.
I say Don't take them to see grammy before she dies.
I had a friend who died of cancer and at the end he was screaming how he hated me.
This was after I carried him into the hospital on my back and he pissed all over me when they originally diagnosed him with ball cancer.
And I spent the year taking him to chemo and blah blah blah.
We have another friend we grew up with who is kind of a dick but kind of charming too who didn't really help him at all.
At the end the friend with cancer was screaming, "I want Kyle! fvvk you Autoprax, you fucking know it all!"
I put the food I brought over so he had stuff to eat and left and didn't talk to him again and he died a week later.
No good dead goes unpunished.
As long as you act on that truth you are fine.