I'm so very sorry to hear that you have had to make this awful decision. Reading threads like yours always brings a tear to my eye, and yours is no exception........
RIP, lovely boy. You will never be forgotten........
I am sooo sorry for you, These free spirits are never really ours they are just a wonderful gift sent to teach us love patience and respect. From what you have written sounds like you both learnt loads together.
RIP you beautiful boy.