My mom said some pretty offensive things to me while my dad was in hospice. It's hard to forgive her for them.
Sometimes people say things they don't mean when their angry. Maybe you should just let it go.
Her personality is pretty direct so I have gotten used to her being offensive. This time it was more personal so it's harder to let it go.
Well, you both have the same blood, so I would advise just to let bygones be bygones.