A good friend of my family struggled with addiction for 25+ years, one of my mom's best friends. Several months ago she hit rock bottom when she ended up getting fired for trying to buy pills of a student (yes, she worked at a high school), and her family more or less turned their back on her. Her retarded (literally) brother found her dead body the other week, she died of an intentional overdose.
So, I'm kinda on the fence with this one, you can't allow yourself to be used and lied to, but at the same time your friend needs to know somebody out there gives a shit about her, even if she doesn't care about herself. It's a tough spot to be in, and I give ya props for trying to help your friend, but if the snake bites twice, it's your own fault...