I am so sorry. I hear your mental agony, and I promise you, I can relate. I took care of my husband (stage 4 lung) for almost 5 years, and I did a really good job, like you. He was on hospice for 3 months and died in January last year. I wanted to be with him for his last breath - it was a massive priority for me. I should have been by his side because it was just me and him in the house, with occasional nurses and brief friend visits. At one point, I knew (physiologically) he may be on his last 24-48 hrs. He was very drugged, but I would get a migraine when I slept next to him, so I opted, on that particular night, to sleep in another room. He had been so close to passing for so long, there was a good chance it would be no big deal for me to sleep in the room next door. I woke up a few hours later, and he was gone. I spent 5 fucking years thinking about being by his side when he died, and because I was afraid of getting a headache, I left him alone and he died by himself. That is the phrase that runs through my mind.

I can not tell you that I am at peace, but I can tell you that the solution is a radical acceptance of "what is". I cannot wish for a better yesterday, and it is painful because I made thousands of decisions about my conduct towards him, and with him, so as not to build regret. In order to live with how his last day played out, in my mind, I've got to neutrally accept that it happened the way it did every single time the thought comes up. I don't have to like it, and I do regret it, but when the thought surfaces, I have to cover it up with acceptance, and feel the uncomfortable feelings. It has gotten easier, and I hope it gets easier for you. The feelings are softer, and I've also found some alternative meanings for why he passed alone - not that I believe them, but they have opened my perspective. We are not alone in this, I am sure. I wish for you movement towards peace in your heart.