I highly doubt that your STBXW would be able to get you thrown out of the house now. She had left on her own choice and I doubt any court would change the status quo on that.
If you really believe that D14 is suffering emotionally and mentally living with her new age spiritual crack pot mother and loser sex partner, then you need to decide whether it is better that D14 lives full time in a more stable environment with you.
My brother got divorced when his son was 2. Both parents had alcohol problems, but the court still awarded custody to the mother since my brother worked full time. It was not until his son was 14 that the battles and emotional torment he endured with his angry and drug/alcohol addicted mother came to an end. His mother had hit him and he hit back.
My brother then tried to obtain full custody. They went to a see a court appointed counselor so as to determine what was best for his son. His son talked first with the counselor (female). Then brother talked with the counselor. Then my brother and son talked together. Then his X wife talked with the counselor. She threatened to kick the counselors ass if she did not recommend custody for her. The mother / son talk with the counselor never happened. The next thing that happened was that my brother, his X and the counselor (with an armed guard) were taken in front of the judge who ruled for full custody for my brother.
My nephew had a stable and great life with my brother before joining the US Air Force a few years ago and he recently go married. My brother is in a happy long term marriage. My brothers X wife kept her anger and addictions. She was found dead in a motel from apparent suicide a few months ago while trying to escape (after embezzeling from her employer) into Canada and being denied.
Pick your battles carefully, but since this now seems that an adolescent is suffering, I think you might need to get some more personal legal advice than what you and your STBXW are currently negotiating.
