So sorry for the scare.
And I imagine that is part of the reason you're still crying...the reality of his mortality hit home in a very big way. Same thing happened to me when my dad had a stroke. It's one thing to "know" that you're loved one is aging and in ill health and could potentially die... it's a whole other thing to run smack into it. Also, you quickly start running over in your mind all the bad things you did, said, etc. to the person in the past and all the things you didn't/haven't done/said and you feel the potential lack of time to do those things and start feeling guilty that you didn't/haven't done them yet and might not get the chance to do them. And you start wondering if they know how much you love them, how grateful you are, etc. But don't worry, hon, I bet he understands.
Just remember, guilt over living your life, a life he helped you build, is not a good gift to give him. Call him and tell him how much you love him...make him realize that he's a very important part of your life and that you wouldn't be the person you are without having had him in your life. I know from experience (both on the receiving and giving end) that having someone tell you that is the greatest gift in the world. Remember, your telling him that validates his role in your life and proves to him that he did his job well...he's raised a loving, caring person who's definitely a credit to him and an asset to society. What (grand)parent wouldn't feel ten feet tall knowing that...knowing they've been successful at the hardest job in the universe??
And take a deep breath...realize that it could and may happen but that it is a natural part of life...that you'll never "lose" him...you'll always have each other in your hearts and in your memories. Also, the greatest demonstration of love to a parent is to be the best person you can be and living a full and happy life yourself.
Hope the tears stop soon.