Dear L.,
If I was you, I would not give up and I would tell her. I would let her know that I will help her getting the help she needs, but that she needs to want the help aswell. You can do all you can, but if she doesn't want the help it will be a waste of your time. Having said that, I think a true friendship sticks around no matter what, in good times and bad times. So you need to sit down and ponder on your friendship, is this friendship that important to you that you will be willing to be there no matter what happens, or is it just not that important to you to continue. Either choice will be hard, if you don't want to continue then you will have to tell her, and if you do want to continue you need to take it all in; and be there for her always.
Before you make a decision, pray and don't do anything until you feel peace in your heart. Maybe you are there for a reason! Such a time as this!
Blessings