"Dead" & a 3 year-old

Picture this.  I'm sitting on the living room floor with my 3 year old son as he is eating a gummi bear (it's actually a gummi vitamin, but he doesn't know that).  He says "Mommy!  Watch this!".  I don't see much happening as I'm staring at him, until I realize what he's doing, and I ask "Did you just swallow that without chewing it?".  He proudly says "Yeah.  Isn't that cool?".  I proceed to freak out and tell him never to do that again.  When he asks his favorite question, "Why?" and asks if he would have to go to the hospital.  I answered "No, you'd be dead."  

Well, since then, my son has asked me numerous times about being dead.  He asked if Superheroes or doctors can make him alive again after he is dead.  He then asked if I will ever be dead.  And then proceeded to ask about each family member one-by-one if they will ever be dead.  I was hoping he wouldn't ask about the 18-year-old cat who likely will be dead soon.  Suddenly he broke out in tears and cried uncontrollably saying he would miss me if I were dead.  And pointed out that I wouldn't be able to kiss him or hug him if I were dead.  And he went on and on about death.  

Now, when he eats, he pulls up his shirt to ask me to look into his tummy to confirm that the food he just ate, is in fact, in his tummy.  This way he knows it's not stuck in his throat and he's not going to die.  What have I done?

So how do I undo this?  And now that I've opened this can of worms, what do I tell this precious 3-year-old about death?  I have tried reassuring him, but it doesn't seem to be working as he has now moved on to having these conversations with his dad.

Well, I must go finish wrapping his Christmas presents.  I can't wait to see the look on his face Christmas morning.

Have a Merry Christmas,

-Barbara-