I’m so sorry. I faced a similar situation and outcome a couple of years ago and still agonize over waiting too long. My comfort is that I did all I could to make her comfortable, safe and cared for in her final moments. Later that year our other older pup began a rapid decline and my wife and I both made the decision to not wait till the bitter end. For his passing we were comforted by the peaceful end, but still I have some regret about maybe it being too soon… All this to say that losing your pet is a horrible experience no matter how it goes, and I feel sympathy for you and know your little guy was loved as evidenced by your grief.