How do you talk to the dementia patient?

My mother does not believe she has dementia. She only forgets the “petty things.” She resents my involvement in her care. Everyone but her realizes she needs 24/7 care and can’t live alone (she’s also an amputee) yet she tells people that she drives, cooks, cleans, etc and none of that is true. When I correct her she gets angry and looks at me as if I am the one who has “lost it.” I try agreeing with her but that makes her angry. She tells me the caregivers don’t know what she does when I know they do. I think in her mind she is in the past back when she was independent.