am i a shitty friend or are they toxic?

okay this is kinda complicated. i’ve been best friends with this girl since 6th grade (i’m a junior in hs now) and tbh she’s always caused some drama. For the past 2 years she always talks about how depressed she is and stuff like that and how she wants to die, and it’s all she talks about. it’s constant. i try to help all the time to the point i’ve told her mom the stuff she’s told me, and she HATED me for that. but i’m noticing she only gets like this when one of her other friends is going through something. for example, my friends brother passed recently, and she somehow turned his death into about her. it’s getting to the point it’s starting to harm me. the amount of stress it’s causing is crazy and she relies on me to help. she knows how stressful it is but she’s kinda like “if you don’t help you’re a bad friend”. also, she called me one night saying she was in the hospital cause she tried to kill herself. i spent my night crying my eyes our cause i felt like i failed as a friend. turns out she lied to me and that didn’t happen. am i a bad friend??