Where's your Mommy?

So Gabe almost made me cry tonight.  I had to work hard not to.  We were reading, of all things, The Belly Book.  There is a picture in it with a pregnant lady with short blonde hair like mine.  This always leads to the question - was I in your belly?  They know Reece was in my belly.

So we are reading and Gabe starts the usual questions -

• was Reece in your belly?  (yes)
• was I in your belly? (yes)
• was Grayson in your belly? (yes)

and here is where it took a new turn...

• was Daddy in your belly?  (no.  He was in MeMaw's belly)
• who's belly were YOU in? (uh-oh...I can tell this is going to be unpleasant for me...I was in MY Mommy's belly.)
• Oh.  Where's your Mommy? (Oh crap.  I feel tears.  She's far away.)
• Really far?  Where? (I don't know, Gabe.  But it is really far.)
• Is she going to come back? (ummm... I don't think so, honey.)
• Why?...

At this point I think Doug realized I was upset so he diverted Gabe's attention.  So the question is - how/when do try and explain that my Mommy is dead?  Won't that make him worry I will be dead?