Oh setterlover that’s really sad news but you made the right decision in horrible circumstances. I am sending a hug because I don’t have the right words to comfort you,.
The positives being he was clearly in the best home a pony could wish for, living his days out as so few have the chance and with an owner who put him first. Keep those thoughts in your head ready to remind you. I’m so very sorry.
I am extremely sad for you and the sudden onset of the issue makes it an harder way to lose an old friend.
Soon you will be able to look back at the all time you had together and how it ended will be just a moment in the whole journey .