Hi, I am sorry for your loss, I know how much it can hurt.
Try to be strong and, as you have already been written, don't give up. Keep looking for your cat, if he is alive, you will find him. Many, many years ago I had a cat. This cat disappeared a week before Yule, and although we looked for him a lot, we did not find him. Under Yule, one morning, he turned up again under the door of the house. It was the most wonderful thing to see him alive and healthy. Cats, especially males, are wanderers by nature. Wait and keep looking for him.
In any case, make a Ritual to the Goddess Bastet so that she will help you reunite with your cat. She is an absolutely fantastic Goddess and has always helped me with cat matters.