Grandfather passed a month ago, grandma still doesn’t know

My grandfather died a month ago from a heart attack (about two days after my birthday) while I was out of town. Most of my family is estranged from one another and no one really likes each other (my mom has issues with her older siblings and none of the daughters or son were really fond of my grandfather either), three days after the burial I returned to my hometown to help my mom take care of my grandma, only to find out no one has told her that her husband passed away.

She still doesn’t know and probably will never know, she’s well in her 80s and has early signs of dementia, It feels weird to be sitting next to her and randomly reminding her that my grandfather’s in the hospital but “will get better soon” every time she asks.

This family decision has also impacted my relationship with my partner who believes she should be told about the passing, they believe we should tell her and at first was very vocal about it until I pleased asked them to stop, I was never close to my grandparents and suffered instances of abuse at their hands so this situation isn’t affecting me that much, although my partner’s reaction and the running out of things to tell my grandmother when she asks are seriously wearing me down.