u/yacccck

my sister, 12 F has been telling me ways she will kill me when "she gets the chance". I am an 18 F who lives in an apartment. When we lived at our parents houses together she would physically attack me, for example when she broke my ribs. She has continuously told me things she wants to do to hurt me. My mother says shes bipolar (it runs in my family) but my dad says moms lying. Theyve been divorced for 2 years from my mother cheating.

Im the only person she does this too. Am i wrong to want to report her behavior to her school or my parents for not acknowledging her behavior? Shes clearly unstable, failing school, vaping/weed, self harms, and violent acts towards me for years.

What can I do to help without ruining her life and my relationship with my family?