Maybe you could write him a long heartfelt letter. That way you can say what you want -- edit the things that come out "too strong" and re-word them. You can't take words out of your mouth back -- but you can use your delete key in a heart beat -- also, you can walk away from a letter if you get too angry or upset and wait until you've calmed down -- where face to face -- you can't do that.

Maybe you'll find that after writting the letter -- you'll feel better too. Obviously, the one concerned about your dad's health is you -- so maybe after you've vented -- it will help you "let it go" a little.

But, whatever you do -- remember that the only important thing is that you love your dad. You can't change him -- all you can do is be sure in your heart that you did everything you could do so at the time of his death -- whenever that may be -- you won't beat yourself up saying "I should have done more".