Being caring and considerate cost you nothing, but I'm a firm believer in "big deposits in the money market at the Karma bank".
I have a feeling you were speaking from the heart, and not trying to gather any sympathy points. You were pouring your heart out to an old, dying woman. There's worse things you could do.
Forget it. Move on. Not even worth 30 seconds in the "self- flaggelation penalty box".
BTW, how do you know you're NOT her favorite daughter in law?