Goodbye Mr. Lunar

I know death is natural, but I wonder what exactly it is. Do our souls die to? Do they go somewhere else? The idea that Lunar (that was the cat's name) just ended and there is nothing left, is a horrible feeling. Sometimes when animals (or people) die, their mouths open, and I think maybe that's how their souls fly out, but when I came home and saw his little body, his mouth was closed, and his eyes were wide open and they weren't reflecting any light. It was like an electronic device which had been turned off... and then I thought: maybe the soul died too? And that felt terrible. But maybe the soul flew out when he took his last breath. My mom said she was with him when he took his last breaths. I wonder what he thought when he took his last breath, did he think "this is it?" Did he mind? Was he scared? Was he sad? Or did he know he was going somewhere else?
When I die, I don't want to know it is about to happen, I don't want to be afraid. I think I will be scared, because I won't want to stop existing, as shitty as life is, I like being who I am. I think my cat really loved being who he was. He had a fantastic and happy life. I don't think he wanted it to end, but maybe he didn't mind. maybe he was ready.