I am sorry to hear. I had a cat called Spog (not named by me) – he disappeared, never saw him again, then Terry (****wit) beautiful but not a brain in her head, ate poison and came home to die, ‘Dillo was next, he also ingested poison, but didn’t die immediately, I had to have him put to sleep, then Djamolidine was run over by a tractor (the shepherd found her body months later and buried her for me), Dandelion succumbed to the liver disease she was born with and I had to have her put to sleep, Frisken was run over, I found her body and buried it, and Ra got cancer and had to be put to sleep. Finally, my beautiful boy Sam (a lurcher) got cancer and I had to have him put to sleep.
I know how you feel, but I can tell you it does get easier, and one day you find that you look back and smile at the funny things they did and it isn’t like a knife turning in your guts.