My girlfriend is an alcoholic (BPD, Birdline, mental mania, PTSD, ADHD, anxiety disorder), how can I help?

Hello, my girlfriend drinks a lot of alcohol, almost every day, including in the morning. She used to drink alcohol so she could talk to people, but unfortunately, it became her downfall, as she's now addicted. It's so bad that she's had a few bouts of alcohol poisoning, and the last time she drank so much that she thought she was dying, and I had to call an ambulance. She also vomited on me.
She bought alcohol again the next day, and again the next. She's only 18, and I don't know what to do.