So sorry to hear, cherish the moments and the photos but for some reason when it comes to a much loved pet I don’t think that makes the pain of missing them any easier.
Sometime this year we will have to make that decision for our 14 year old dog. Failing heart valves, Dr says at some point this year his heart medication will no longer be effective. Not sure if he will see his 15th birthday in the summer. Mentally we try to prepare but can’t imagine him no longer being in our home.
One thing for sure, like you did. we will be by his side when the time comes. He became part of our family not much later than yours at the end of Sept 2010