I would point out to her that you cant afford to help her in any way shape or form and is she persist in going in this direction then she will have to support herself totaly.

She is now nineteen and is getting to the point where she has to learn for herself and by helping her out financialy you would be shielding her from her poor decision making, as parents we are all tempted to do this with our children we bail them out of their problems financialy, my feeling is if they are old enough to disregard your advice they are old enough to cope with the consequences (sp is up the wall a bit today) ......