This happened to my cat a while back, it was supposed to be a checkup because he was acting strange, but it turned out he was pretty far along with a disease and had to be put down the same day. RIP Zorro. I wasn’t even particularly fond of him, as he always bit my ankles, but I still cried for days after.
I’m so sorry for your loss. I lost my cat back in the fall to cancer and I still miss her everyday. You never stop missing them but you learn to treasure the moments you had with them.
Sorry :(