Treasure her. Tell her everything you want her to know. Let her have no doubt that you love her. Continue to show that love in ALL your actions, no matter what. Sometimes they will be sad and angry that their life is coming to an end - be there and listen and love them more. Hopefully in heaven, you will all be reunited again.
Sometimes it is difficult to find the right words...but you stated it beautifully.
My prayers to you