It's hard but it's easy.
It's obvious, but it's also hard to face...
The answer to your question sweetie is this:
If you can do it, you can, If you can't - you can't.
The bad news is that YOU ARE ONLY HUMAN.
The GOOD news is that YOU ARE HUMAN, and YOUR MOTHER is HUMAN, too...
There is more to loving someone than taking care of them. ANYONE can do the physical work of care-giving.
But YOU are her CHILD, and NO ONE CAN TAKE YOUR PLACE IN THAT ROLE. NO ONE ELSE CAN LOVE IN JUST THE WAY THAT YOU DO.
So, in my opinion, that's what YOU should do - the one thing which ONLY YOU can do. Be there for her as her CHILD.
Wherever She NEEDS TO BE.
"Mother," to whom you once made a promise ... is no longer, just as "Child," who once made a promise, (and is now inexorably changed) ... is no longer...