Sparing everyone the details, my niece asked me if my husband was unhappy with her being with us.
Basically, yes - and if she wanted it different, we should talk. also said I thought she was living there all on her own terms and that it didn't feel very good to us.
Result: defensiveness, retreat to room, no progress, accusations, I'm causing her to be depressed. blah blah blah
It's called manipulation and she is calling the shots, playing the guilt card to make you feel bad for wanting her to leave.
How do I know this? Because my son was the king manipulator and I see myself in your story.
It won't stop until YOU say so. She never will...never. She has her soft place to fall and who knows what schemes she may be up to on the internet but I'd be suspicious of that too.
My thoughts are to give her a deadline to find her own place, or check into rehab...and stick to it. Remind her often that the day is approaching and that when it comes, if she doesn't leave, you will change your locks and no longer allow her to come to your place. Sounds tough but trust me, she's tougher.
"We" are not their only option, we are not even a good one. Here is a list of real options that you could hand her.
Rehab...the Salvation Army programs are free and very good. Not sure where you live, but in Canada most rehabs are paid by government health ministries.
Sober house...she will need to investigate what may be available in your area.
Get a job, any job, and give you the money to set aside for first and last month's rent somewhere. I say this because she may say she is saving and then will have some boo hoo story of how the money was lost.
Women's Shelters also offer training, and a safe place to stay, sometimes when abuse is not in the picture or she could meet with a counselor there for suggestions.
If all else fails maybe pay first and last for rent somewhere for her and help her move. This will get her out and give her a chance to decide to work to stay there or give it up and live on the street....her choice.
Wow, I just re-read your post and noticed the part of you doing this for 14 years. That's even longer than I went with my son before the crazy circus left town.
I think that you may want to look at some options for yourself too, like maybe going to meetings (Al-anon, CoDA, or family meetings) and find your balance and get some backbone (I say that with love in my heart because I have been where you are and I know your pain).
This will never stop until you say "enough" and mean it. You have the power to reclaim your life. You are not responsible for her bad choices.