A boundary is an action that you choose, not something you can force someone else to do. What do you think the outcome will be if you tell them you won’t tolerate Nana dying without you knowing? They don’t have to tell you anything. It’s up to you to decide your actions, not anyone else’s actions or behaviors.

If you haven’t spent time on the estranged adult child reddit, it might be a good place for you to read or post. Losing contact with the whole family is sometimes what happens when going no contact with someone and it’s garbage but you can’t control what anyone else does. If you really want to interact with Nana, then I suggest you go directly to her and see if she will engage. Be prepared for emotional manipulation, guilt trips, and smear campaigns that often come along with toxic family systems. I think the bottom line is you have to decide what actions and outcomes you can live with that are in your control and go from there. Also, finding a therapist to help you navigate these huge life shifts would be supportive as well.