Joshua88,First of all congratulations on discovering that you will be having a daughter, what a joyful time for you.
Death is an inescapable part of life and I suspect that "Grandma" would not want you to feel bad when she dies as she would not want to be the cause of your sadness. Grandma would want you to enjoy your impending parenthood and all she would ask is that you remember her fondly with love and tenderness.
Shed a few tears when the time comes and someday when your daughter is old enough talk to her about the wonderful woman you called Grandmother.
Be well and again congratulations on the good news.
Gentle hugs,
Kitt