I am so sorry Ken. I am sure you already have a good picture of her you can frame and hang in the appropriate place when her time comes. It is probably too late to get the pup back, as I am sure the pup and baby have bonded. She was so lucky to have had you and your wife in her life and you guys were lucky to have had her. My heart goes out to you guys --sad time.
There is comfort, even just a little, in knowing yoou are making the right decision for your beloved friend, even though it breaks your heart. Comfort and strength to your family @ the end of this long, loving journey.
If humans could hold a fraction of love our four legged family members give, the world would be a much better place.
Sorry to hear Ken. Has to be one of the very few decisions that tugs the heart as much as it does.