I'm so sorry KC, I SO wish I could suggest some other way out of this (along with everyone else I think), which would give him a feeling of being loved, but until you (and the rescuer), he would never have had that, and I suppose, not being able to see your expressions or hear the tone of your voice, he can't understand how much you care for him, he looks a sweet little thing, but what a horrible existance he had, you've given him all you can, his time with you has been calm and stable, well fed, warm secure place to sleep, to just go to sleep now and not have to wake up, well, when it's my time I hope that's the way I go.
Well done in all you do.
Take Care
BTW, how is Juno(?) the blind dog who had the operation doing?