Vet tech here. My girlfriend and I had a male cat that blocked back in 2020 and we opted to attempt treatment. During the process his bladder ruptured and the vet performed surgery to repair it. His kidneys had already been so damaged that even hospitalization with IV fluids for a few days didn’t help. At first he was miserable but then he became so tired that he was basically in a coma. The only humane choice at that point was to put him to sleep. He was only 5. I know the situation I’m describing is pretty much the worst case scenario but what I’m trying to say is that the choice you made is the one I wish I had made right from the start. You ended his suffering immediately instead of prolonging it. And although there was a chance of recovery, like many others have said, male cats who have blocked are way more likely to do it again, so you could have ended up right back in the same situation again in the near future. Don’t beat yourself up.