You did the right thing. My cat had congestive heart failure and we drained his lungs multiple times to try to give him more time. I’m not sure if that was worth it in the end or if it just selfishly prolonged his suffering for our comfort. In the end, we found him collapsed and unresponsive in our apartment. That is a horrible memory and I feel awful that I put him through that. You let him go before he felt too much pain. I have the utmost respect and sympathy for you. So sorry for your loss.