My girl has an addiction. I need help!

​So me and this girl have been going out/seeing each other since Valentine’s Day. She’s real cool and fun. I even asked her to prom and she said yes. This isn’t the problem. The problem is she is addicted to alcohol and weed. I’m all for the two when you use it every now and then, but she does this stuff on a daily basis. I want to talk to her about it, but I don’t want her to flip out or just stop hanging out with me because I bring it up. Bottom line if this gets screwed up i’m without a prom date, no sex, or any make out time. On the other hand though I think she might kill herself with the amount of week and alcohol she’s taking in on such a regular basis. 

I really just need a bro’s advice right here. Please help.