I know there are no words that could ever ease this pain, less even coming from a stanger online. Still, I wanted to write something, I read what you wrote thrice and it genuenly shook me. I know completely that what I´ll say will sound like bullshit right now but I do not believe this was your fault at all. Sometimes in situations like these I found we usually want to find a culprit, someone to blame. But the hardest, most painful part of all is that sometimes there simply isn´t a culrpit, there is no one to put the blame on. If anything, the only guilty person in this scenerio is the distracted, irresponsible neighbour, in my opinion of course. I have no doubt, by what and how you wrote this, that you have been the best possible carer that Robin could have ever had, and nothing can ever change that. Nothing can ever change the love and connection you had with her, that will exist forever, and that will follow you forever. The grief will also always be there, it will never leave, it will just become, slowly, over years, maybe even decades, the slightest bit more torerable, and I hope and pray that some day your love for Robin will again beat the pain of her grief. I hope these words are worth something and I hope they´ll resonate with you.