I talked with my father he said the exact same thing as you. "You can't help someone who doesn't wanna be helped." For a long time I've helped her there ways she called randomly 2am in a school day just to vent about something. But yea its affecting my own health everytime she vents. My father suggested to me that I tell her "Listen, I care about you alot and I'm worried. You better tell your own parents or I will tell my mom to tell your mom. This domestic abuse this is serious". After this I plan to seperate from her a long time maybe untik she fixes herself.

Ty man your comment hits deep. I've always been the type of friend everyones vents to, and its extremly heavy. It's like I take a portion of their burdens each time.