Hey.
I remember about...a year ago?...we commiserated. Your Mom was still out driving around, my grandfather was still out driving around, relatives being unreasonable...I'm glad for the update on your Mom. (And if you want I'll vouch for what you said with your sister.

). Gramps ended up in a one-car accident shortly thereafter and ended up in a nursing home. His son felt he should stay there, my Mom wanted him out, and I (being a SAHM and all) was the tie-breaker, and he's home now. Was a long process getting him back there though, and everyone still pitches in, so he's only about 30% 'independent.'
I've been watching my uncle do and say some incredibly nutty things though, through this...he's not around more than every other weekend, he's always been known as the 'high strung' one, not easygoing at all...can't handle it. IMO only. I know his heart is in the right place with his Dad, and maybe with us too (that's me being kind) but he
cannot just 'do' what has to be done for one or two days without lashing out at people in the process. And sure, he's the one without the problems the rest of us have. I was separated, almost filing for divorce at the time, my Mom has multiple sclerosis and my Dad was recovering from back surgery...ok, we can deal...but wait! Uncle has a trip to Florida planned and may have to reschedule!

Nothing against Florida trips of course, just saying his priorities have always been obvious and self-centered. My Mom is a saint and reminds him gently, 'we're here every day. yes, we know how it is.'
(I went off like an M-80 back in August and things have been really chilly since. Probably not the best move on my part.)
So, anyway...yes. If she's not been one to take your personal issues into consideration before, why would it be any different now. It's your call to be the calm one, the 'bigger' person, and say 'I understand how hard it is for you, and when I was able to do those things for her, I did them. Things have changed now. Drastically. I'm sorry.' Calm. Collected. Maybe she regretted what she said two seconds after hanging up, who knows.
You could also escalate it into a battle, but I've been there, done that, found the whole thing a waste of time, actually...*I* know I've done as much as possible, Gramps does, the people who matter most do...that is what's really important. Rant here! We don't mind.
Good luck.