Sometimes getting a change of scenery is helpful, so don't beat yourself up about having your D go stay with Aunt. You probably needed the break as well. And the thing with BPD, is that it is one big game of Heads I win, tails you lose.
There are a few advantages to them turning 18.
![Doing the right thing (click to insert in post)](https://www.bpdfamily.com/message_board/Smileys/default/bpdfamil-01.gif)
One is that it is a reality check, that they aren't living at home because they have to but because they aren't ready to move out. Some kids comprehend this somehow.
You can have conversations around planning for her to move out and so on, not in a scaring her or threatening her kind of way, but "what can I do to help" sort of way.
If she is absolutely refusing therapy, etc, after the age of 18, there is the option of insisting she either start making some changes or move out. You might not go that far, but it is something you can have in your pocket that might make you feel less helpless.
After 18, you are not legally responsible for them or their choices. You get to choose what you will help with and what you won't.
My BPD D 16 is just dying to turn 18 and be free of me. I don't think it will work quite like that, but I'm looking forward to her not being my LEGAL responsibility anymore. Maybe that makes me a bad mother. I am definitely a tired mother.