My mother refuses to apologize or exhibit she even cares for her adult son, what do I do?

I'm 36 and have found myself estranged from my mother & aunt after my wife & I asked a nurse to evaluate my grandmother for dementia. She'd blacked out & fallen 4 times before being put in rehab for a broken leg. My mother called & chewed me and my wife out on our anniversary no less, deeply hurting my feelings. I wrote 3 letters to my mother, apologizing for not consulting her first, expressing how hurt I was, & how we still felt she needed to have grandma properly evaluated. She ignored all of my letters for many weeks. I went to talk to her on 2 occasions & each time she refused to apologize for chewing us out, or for ignoring my letters, and just made me even more angry. Despite my pleading, my mother refused for months to get grandma evaluated and when she finally did, she was found to have some kind of dementia that she's now getting medication for! After 4 months, my mother continues to act uncaring for how she's hurt me & is completely unapologetic. What can I do?