@violet218 I wrote a really good message, but it exceeded the number of characters....so oops. :/
I'm praying for you. God is right next to you, ready to help, so if you haven't already, ask!
Most of what I have to say revolves around prayer. I can't say exactly what you should do, only show you different sides of the matter and show you Christ.
God might be calling you to minister to her, to help her change her ways. Even if He is, though, this can't be a healthy friendship. He might be calling you to distance yourself from her, still calling on the power of prayer.
Either way is hard, I know. You shouldn't stay around "danger people", even if they are your friends, so I'd advise giving yourself some time off.
I'm praying for you. Depression is a hard thing also, and staying around someone who makes you depressed is also hard.