TD, you went the extra mile for this fellow, what a large heart you have.
I too had a feral put to sleep because my hands were tied with what to do with him. I had watched him for about 5 years living around this complex, most likely eating out of the dumpster here. Last year I had been putting food out for cats, and when I saw him through my window I was shocked at how thin he was, and that he had open wounds as well. It was xmas eve when I took him in. I had no place to keep him if he had been cleaned up, he had been neutered at some point. I couldn't release him as winter was upon us, and couldn't trust at his age that he would survive the winter with his emaciated state. I believe you ended the cats suffering, recuperation would have been a very long road, if he survived all the surgeries. I think you did your very best and he is at peace now. Please know you were his angel for him, food, shelter, and care. You went above and beyond so many others. Your 3 cats are very lucky to have you. May you find peace.
"People disappoint, dogs never do" - spiritdog
"You MUST be your pets ADVOCATE, if it doesn't feel right walk away." - spiritdog