NAH. I know this will be unpopular. Ultimately this isn’t you’re choice. It certainly is your choice to move out. But here’s the thing. You might actually end up loving a new little sibling. I speak from experience. I never forced my older daughters to babysit or expected them to raise they’re siblings, who are 18-20 years younger than them. Happily, they chose to spend their time with their new siblings and it is a happily ever after story. Nobody owes you anything in this life. You do have to make yourself happy. I helped the girls as much as I could with their college expenses and everything I could. Ultimately the choice is yours. No assholes here.