How should I handle insensitive family members throwing my mental illness in my face?

I have been suffering with anxiety and depression and diagnosed with bipolar disorder and every time my no-it-all grandmother gets mad wih me about the pettiest things the conversations ends with an argument and her telling me to go and kill myself or starts calling me crazy, It gets me so angry and she knows it, she knows that it hurts me and she seems to enjoy saying hurtful things regarding my mental illness I know that I could say some very hurtful things to her that would probably make her hate me for the rest of her life but I am trying not to go this route. However, I am starting to feel that the only way to handle her is by pouring salt into her wounds so to speak. She has lost two sons within the last 18 months and I know she is very sensitive about her son's death. I want to hurt her emotionally just as she has been hurting me. I don't know what to do with her she has done alot for me over the years and I guess I am a dissapointment since she doesn't really understand mental illness and thinks anyone with it just hasn't prayed enough. What do I say to this no-it-all woman to make her stop saying all of the insensitve things to me about my illness?