I read thru your post and I suggest counseling for you, and her mom...if she wants to get help.
It would be overwhelming to be on such an emotional roller-coaster. Even though you didn't mention her having drug or alcohol addiction, I wonder if this is how she supports her habit? Even if they aren't involved, you still can't change or control another adult,
I go to a 12 step meeting for family or friends of addicts. It is really very helpful to put things in perspective. Parents dealing with their child's poor behavior, addictions, mental health issues, criminal behavior...all have the same things in common. Their child's issues is hurting the parents hearts, health, jobs, finances, other relationships. One has to find away to let go of all pain, detach, have boundaries, take care of yourself, make a life gor yourself and find some happiness for yourself.
There is a great article about detachment on this forum...it is always one of the first four posts. Read it often. Good luck.
