This is the first time I have visited this board and I am not sure where to start. I am married to a wonderful man, when we were married 4 years ago, of course I knew he had 2 adult daughters (at the time they were 19 and 21) The youngest lived with us, and she was in college, not a big deal I also have 3 children and I let all of them stay at home while they were in school.
The first 6-7 months were fine and I got along very well with her I did notice that she was out every weekend drinking with her friends and although she was underage I just thought that
1. I am not her parent
2. Who doesn't party a bit in college, by the time we were married 9 months I started noticing little things like the wine that sat in the fridge for months was disappearing and that the bottle of rum in the cupboard was now gone. Since I am the "step mother" I didn't feel that I should bring it up so I spoke to my husband and we all sat down together and talked about it.
She was sorry she figured since we didn't drink it and she was supposed to bring her own it wouldn't be a problem. She replaced it and promised to not do it again. 
Soon afterward I came home early from work because I wasn't feeling well and found her home with a friend and her boyfriend, when she was supposed to be at school, she responded with she over slept again no big deal people do that all the time when they are kids, but for some reason something inside me said "something is not right" a week later I got the mail sure enough, a letter from college saying she had failed all her classes because she wasn't showing up.
My heart sank, 2 nights before I had "helped" her with an english paper she had been dropped from english a month earlier so obviously the lies had started.
By the end of the screaming between her and her dad it was decided that if she wasn't in school she would need to get a job, she did things seemed to be better when her sister came home to visit (she was in another state in college) we found out that she had been talking to her sister about what was really going on, she was drinking nightly even when she was at home alone in her room, and she had been stealing from the liquor store when she didn't have cash and on top of all this news we also found out she had been cutting herself.  
We all talked about what we should do and because of the situation my husband also called her mother (in this case the tables were turned he had raised the girls and was a single father their mother had very little to do with them and the courts had made sure of that because she had remarried shortly after the divorce to a sex offender...I learned about it THAT day and thought WHAT THE HELL HAVE I GOTTEN INTO?!)
We decided that we should talk to her and see how bad she had cut herself and get her some help.
She was furious at us.
The cuts were much worse than I had expected, deep, some infected and she needed medical attention, my husband had decided that it would be him and him alone that would take her to see a dr. but while he was gone his other daughter called mom and whatever was said, convinced her that her sister should be the one at the hospital with her not her dad.
Another fight ensued at the hospital and since I was not there I don't know what was said or done except that my step daughter would be leaving our house and going to her mothers.
I know this sounds evil but I was relieved. The very next day while we were out we came home to the sex offender and his ex wife inside our house loading her bedroom...furious is a understatement.
We didn't speak to anyone for a month when his daughter called to see if he would help taking her to meetings, of course he would, and we got involved with therapy and for a while things went well.
She was with her mother a little over a year, when we found out that she had moved in with her boyfriend who was a wonderful and supportive man she had been with since high school, no wrong, she had cheated on him and this was a "new" guy she was moving in with. Within 6 months she was arrested for battery against him and in jail, back with mom after she was "lucky" and the charges were dropped.  
Because we were not in the picture daily we found out that she had been stealing from her job, was fired started another job was fired for not showing up, was drinking, stealing from her mother, and they had enough, she was then moved to her older step sisters house, that lasted a month when we get a call from her crying because she was kicked out for stealing money from her 8 year old nephew.
After a very long talk and finding a rehab here that would take her we agreed she could come if she went to rehab and stayed in a program.
Things were fine at first, she was to go into the rehab 20 days after she got here she was seeing a dr. and going to meetings, we watched her like a hawk 10 days after she got here her dad asked her if she wanted to go with him to help out one of his friends, she jumped at going, 2 hours later they get back home she runs to the bathroom my husbands face told the story of something going wrong, as it turned out she had stolen a bottle of vodka from his friends house drank half of it in the bathroom and was caught by his friend, I went to the bathroom to talk to her she opened the door and she had cut herself again and was crying for me to help her.
I will admit I felt nothing but disgust. She plays this game every time she gets in trouble, she cuts herself.

Now some background on me and it may help to understand a little, my youngest daughter was 20 she had a full scholarship to a fantastic college back east, she was visiting family for the Christmas break in 2006 her and her grandma had driven to help her grandpa with his truck that had stalled, on the way back from helping him they were hit head on by a drunk driver going the wrong way on the highway, her grandma was killed instantly and she was seriously hurt, a month later she had surgery to repair her broken hips, she died during surgery. The drunk that killed them served 2 years. 

I have a sister that is a functioning alcoholic, and a brother that is in prison for his 4th DUI (And serving MORE time than the drunk that killed my daughter. Justice is served.) I know that I am less tolerant than most, but where do you draw the line?

An ambulance was called (She had cut so deep on her thigh you could see the muscle) they talked to her and she became nasty and fought them so a sheriff was also called to help, we were told they would stitch her up, keep her on a 5150 for 3 days and would we take her back then?
I have had enough, I told them absolutely not.
Her sister has finished school and has a baby and lives nearby, she went to the hospital with her dad and we all talked about how this was it, we can't keep taking care of her we need to stop and she needs to take care of herself, found another rehab that specializes in mental health as well as alcoholism and she signed herself in that night. 
2 weeks later she was kicked out of rehab for reasons we can't find out because she is an adult..and walked to her sisters house that despite saying she would never take her in, took her in.
Flash to Thanksgiving, while on a trip to her mothers for the holiday she sneaks away steals a bottle of gin drinks the whole thing gets into a fight with her sister and she's kicked out of her sisters house now.
 
In comes the very last relative she has left, grandma who also says she would never let her stay with her she needs help blah blah blah.
She moves in with grandma. This morning while I am out walking the dog I get home to a message of "Please call me as soon as you get this" from grandma. 
I knew and I know she's up to the same old same old crap, and for some reason nobody believes she's doing it until she lives with them and starts destroying the normalcy they have.
I also know that she is going to want us to take her back in. We won't, which has made us the "bad" guys. I don't know what to do now and once again am sick. 
I realize that I am not her "family" but as much as I have vented on here I really DO care and it breaks my heart to think of her on the streets, but we can't do it again, I don't know what to do and have been ignoring that message for 2 hours now..