Its IMO also necessary to understand that detachment, just like boundaries, is about you and for you. Detachment is something that is good for any individual in any relationship (not just romantic ones). As divorced and fully separated I am still working on detachment. Detachment from XW sure, but my main detachment focus is actually on my father. And it’s funny, emotional detachment with my father has in some ways brought us closer. We are more equal.
Detachment isn’t about not caring, it’s about acknowledging what you can control and learning that you are only responsible for your own happiness.
Citation from another great post here: Leave them to their journey. You walk yours. You wont die from this. You will be reborn.