I am so Hurt

(edited to protect family members) Ok, I thought I would edit the post to make it more anonymous...A family member is using stuff that she says my dead mother said about me to hurt me...how do I handle a situation like this? It seems so evil to me to use someones dead mother to try to emotional attack and hurt a person.
Also: When my mom died (of terminal stage 4 lung cancer), This family member asked my sister..."Do you think they killed her?" Now who in the heck is 'they'? I am assumming she means me, my husband and my dad, because we all lived in the same house...I dropped it and never brought it up to her. Guess I had to get it off my chest since all this happened, how do I emotionally get past this? I havent' slept all night.