The reality is that she desperately wants to be a kid (when she feels like it) and be taken care of while also doing all the adult things she does.
Hello, darkness, my old friend. I've come to talk with you again.
I'm sorry that you're going through this, but I'm glad I'm not the only one who is with my kid. DD 19 positively lives to tell me, "I'm an adult, I'm 19", yet she still wants and feels entitled to:
free stay at our house
the car we purchased for her use that we pay for
health insurance
car insurance
food
shelter
cable tv
college expenses.
My thought is that she wants to be treated like an adult but taken care of like a child.
Now, don't get me wrong, I think that most, if not all young adults (18-23) struggle with this new independence and sense of self. Many have the same desires, to be treated like an adult but with some financial backing from their parents, but with OUR kids (with BPD) it's presented with such demand, almost hostility, that it really turns us off.
I had to have a conversation just last night that living at home with everything being paid for is not actually being an adult.
So, what do we do? I don't know, I'm currently going through it at the same time you are. I hope you figure it out, and when you do, let me know what worked, ok? I'll do the same for you on my side.