Your children are affected by everything that happens in the family. Being honest can be painful. Nevertheless, dishonesty, even with the honorable goal of protecting the children, may be the single biggest mistake you as a parent can now make. There may be nothing more important in their lives than that they continue to trust the two people they love most.
Children are stronger than you think. Your children love you. Because they love you, they can handle what is coming; they are much stronger than you think possible. What we must do now is build on that love and so build that strength.
Three things to tell your children
Tell them Grandma is seriously ill.
Tell them the name of your disease.
Tell them your best understanding of what may happen.
However grave the illness, hope comes along with every diagnosis. And it is neither wrong nor dishonest to pass this hope along to your children.
All life is terminal. Even if one's own timetable is tragically shortened by a medical diagnosis, the end is not yet. Don't try to shield your children from making the most of that time."
Explain the disease on the child's level
Tell them three things, and keep telling them:
Nothing they did caused the disease
They can't catch the disease from you
Making time for your kids when you don't have time:
Set aside a time - ten minutes at night around bedtime and bath-time
Try to keep doing the family things you all do together: take a bike ride, walk to the park, etc.
Important warning signs that a child needs help:
Major changes or disturbance in sleep.
Major changes or disturbance in eating.
Appearance of fears that weren't there before.
Developmental trouble: loss of skills, falling grades, etc.