How do I leave a relationship?

How do I leave? Idk how to start. I been talking about divorce with him for a while im just…scared? Idk i feel like im stuck i have 2 kids and 2 cats. I absolutely want to take my 2 cats there’s no way i can leave them behind. I just can’t be with him anymore. My mom said screw the cats just get out of there but these cats have helped me and are my babies I can’t do that to them.