Setting boundaries with family is harder than I expected

I told my parents I can't do weekly Sunday dinners anymore — I need the downtime. You'd think I announced I was moving to another country. The guilt trips, the 'after everything we've done for you,' the cold silence. I know the boundary is healthy. I also feel like a terrible daughter. I'm not cutting them off, just trying to protect my energy. Why does doing the right thing for yourself feel so wrong? How do you hold boundaries when family pushes back?