It is never easy losing a loved one. Having such a history behind a loved one makes for two things: First, it is that much harder to say good bye. Second, as a loved one you have that more of a reason to stand tall and be proud of him and his service.
Both of my g'pas were in WWII and the older I get the more I appreciate them and their kind, including your own grandfather. Most of us have no clue what they went through.
May his passing not leave you in tears for long, but instead may it provide a platform in which you can stand that much taller and that much more proud of who is was and who you are. Share his story and pass it along.