Does anyone else know a Narcissist who clearly lacks all empathy but hotly disputes this , and claims to have masses of empathy?

My mother has NPD and has alienated everyone around her. At one point, last summer, she had successfully cut out everyone except her dog and her hired help .

She has damaged my father ( who has never had a relationship with another woman since divorcing 35 years ago) she has just buried her second husband ( who committed suicide after a very dramatic row with her) she stopped talking to her own mother 10 years before she died and told me to stop being silly when I was upset when she died, citing her reasons : Dead is Dead. She disowned her sister and two brothers, myself and her grandchildren. Only my 30 year old half sister remains as her sole source of Narcissistic supply ( in exchange for financial support).
I have had to consciously protect myself from wanting a relationship with my mother as I know it only leads to pain and drama. Unfortunately that means sacrificing my relationship with my sister too.

I'm sad to think she will die a very lonely and sad lady.