Im Bad at Leaving

Hi everyone. Im 23. Im a stay at home mom. Im thinking about leaving my fiancé. It sounds so simple, if you’re thinking about leaving, then you should leave right? How do you leave someone you’ve been with for years. How do you leave someone you have 4 pets with. Since I’ve been a stay at home mom I have had no income. Which means moving back in with my parents. I hate it there. I’ve never learned to drive. He’s drove me everywhere. Leaving means starting completely from scratch at 23. Where do I even start.