Where's the balance?

I just watched some of the "Dancin' in the kitchen" video I have of Ani, Nate & I dancing in the kitchen.  I find absolution in the size of Nate's smile, his joyful squeals, and the totally trusting way Nate and Ani hold my hand to dance.  I've remarked before to others how awesome the responsibility is, of being a parent, when my children have looked up into my eyes.

What is the balance of accepting Nate as no longer being with us vs. allowing myself to temporarily "forget" our situation by losing myself in things like reading, blogging, video games?  How do I stop feeling guilty for taking small diversions to take my mind off of the enormity of our situation?  I can't go through life always meditating on how Nate is no longer here, that's not fair to those who "need me to be here".  I also can't bear the thought of forgetting the least little thing about Nate (or Ani's previous life).