Oh, Heather...I'm so sorry I didn't see this until now (where the heck have I been)!
I'm so, so, sorry for your loss...
PLEASE don't say that you couldn't help her, you did everything that you could for Zoey (and more!), you gave her all of the love a dog could ask for and you freed her of her pain & suffering...a lot of people couldn't do that, it was an act of compassion and I admire you for that!
Know that Zoey is now resting comfortably, and that she's watching over & and Dan...and will be forever
I'm so sorry and if there's anything we can do for you...you know we're all here for you
Big (((((((((((((((((HUGS)))))))))))))))) to you Heather, sending lots of thoughts your way
RIP Sweet Zoey, you will be greatly missed