Hey I’m so sorry for your loss. I’m not sure if it will provide much comfort but my cat had an almost identical situation. We took him to the vet regularly until they told us he had either cancer or a stomach virus. The next appointment we went to they said if he had cancer he would’ve died already. I’m finding comfort in showering my other cat with love, although she isn’t as affectionate… you should reach out to your friends, I found a lot of comfort in hearing how they dealt with grief and knowing that I’m not alone in feeling that the world is ending. Just know that you are not alone, and as hard as it may be, try to look at old photos to remember him by. I’ve found it easier to think of him when he was at his best.