I'm worried my sister is going to die?

My younger sister Katherine who is only 15 is on a destructive path and I'm very scared about what could happen. First off all she got pregnant and had a miscarriage and she keeps taking anti depressant pills and overdosed last month and almost died. My older sister Alexandria caught her popping more pills. Alex is a recovering addict but has been clean for 5 years. She tried to have an intervention but it didn't work she told me her baby dies so she wants to die. What should myself and my family die?