My condolences, m1. Feel the same about my own late father.
Your hero did not die. Not the part that made him immortal. Check the mirror for that. Look at your siblings, your children and theirs.
When my wife passed I was left with many feelings I couldn't cope with. I still find it hard at times, but with the help and advice of friends like Mark and Ed I am learning day by day.
You'll find that the severity and suddenness of the attacks of raw grief will become less frquent with time. Let that happen. No one can tell you how to grieve. The best to hope for is friends who'll listen when you speak and just be there.
Just give it time. That sounds hackneed but it's true...believe me...I've lost both my parents. Be grateful for the times you had, without regrets (I doubt he'd count anything against you), and that you had the time to say "Goodbye".
Have faith, for the part of him that G-d gave him returned to it's maker: as all do.
Love to you m1, and an easing of the suffering. Rest easy: His passage was eased by The Shepherd.