Wow, PaperDolls. I have no particular advice except that you are in a pickle! And big hugs from me. Trust your intuition on this one, I would guess what you "suspect" is really happening, and has the potential to get worse. At least she hasn't yet asked to move in with you! ; )
Detaching from it seems the only way to not let it wreck your serenity. And as much as it sucks for the baby, until something significant happens, there isn't much you can do right now anyway.
Prayers for a positive outcome,
~T