Apple,
I, too, send my deepest and sincerest condolences. The loss of a parent (or parents) is, without a doubt, one of the most difficult things imaginable. Only someone who has experienced it can truly understand the effect it has for the rest of one's life.
As you've said, her suffering is truly over. She is beyond any and all earthly pain and illness. And you and your sister were with her; when the end came, she was not alone. You were there for her.
I hope you are hanging in - certainly these are the most difficult times, but if you need the GBB, we're here if you want to talk or even just vent.
Signor V.