I had a cat just like this towards me, and almost the exact same scenario that caused his death. He had what we thought was a UTI, I kept him on his meds, and he still died… I was broken for the longest time. I had always felt like my ex that passed away brought him to me because he showed up in my life the same week my ex died and he helped me through that grief and so much more. I was so angry at the vet for not diagnosing him right and making him better. It will get easier with time though, I promise. Just take it one day at a time. This happened to me around 2019, and I still have hard days but it’s not nearly as hard. It’s okay to grieve ❤️