OMG... I was out of town and missed this...
(((((Chris))))) I am so sorry that you lost your beautiful, beloved Cleo!
I have lost so many over the years. And the one that haunts me the most was a sudden death similar to this. Squeaker was literally fine one minute and dead the next. There was no warning, and absolutely nothing we could even try to do. My head knows that there was nothing that we missed seeing or doing, no way to predict it, and nothing we could have done. But my heart still feels that we let him down...
My consolation (and it's a huge one) is that it was so very fast (it felt like hours, but was actually literally about 30-seconds), we were right there with him, and he did not suffer. I hope that you will be able to find consolation and peace from that same thing. Cleo went quickly, at home, in your loving arms. For her, that was a wonderful way to go.
Cleo will always live on in your heart!
Sending many hugs and prayers...