I feel your pain, I love my dogs more than most of my family members. Death is an eventuality, that's why you have to make the most of every day. Sounds like you love your puppy and that's all that gizmo is ever going to care about. I know the day will come when both Yuki and Cammy will put me in the same spot that you are in now, and I loathe the day that it happens and honestly know I'll be a fucking mess. Just do what you think is best for Gizmo