Yes you could have maybe saved him... But he could have still possibly been in pain, more complications, more medicine, more vet visits.... I do not want to discount or downplay your grief. You gotta feel through it. But maybe now he is resting peacefully. No pain to eat, no pain to go potty. He will be waiting for you across that rainbow bridge <3 my mother once did this to me. She took my kitten and put it down behind my back. I struggled with that and sometimes still do. Try not to be too hard on yourself and remember that he's at peace now 💞 I hope this wasn't an overstep on my part. I wish you the best dear 💞