I'm going to leave my ex for a younger woman whom my ex used to babysit 20 years ago
Why would you want to leave your ex?
She is much more attractive than my ex.
It is fine to break up with someone if you find someone else to be with, but you should consider why you're doing it. Attractiveness can be a shallow reason to leave someone for another person. It's better to think things through and be respectful of your ex.
Fair enough!
If you do break up, try to break the news to her gently. Breakups can have some pretty emotionally charged moments. Be sensitive and kind.