Scott, we understand your feelings and are so sorry for your loss. A good friend of mine had to make the same decision today for his ailing 18-year old Lab. Just take comfort that she'll be waiting for you at the Bridge. A friend suggested the site
www.petloss.com a few years back, and while words alone can not take away the pain, there are some good things t read on that site.
She'll always live in your heart. Take care buddy.