Hi! I'll be glad to help you with this issue. Because you were offline, the system reverted to the question/answer format so I'll answer you here, okay?
I can imagine how distressing and, yes, devastating, this situation must be for you. You are clearly an intelligent, level-headed, caring and loving person. And it feels like you've stepped into a totally dysfunctional situation. I think your assessment is correct:
You have stepped into a dysfunctional family situation. How dysfunctional is not possible for us to diagnose here, nor for you to assess with the limited information you have. Let's start with the scariest things:
We don't know if she was molested, or if incest has occurred, or if there is any ongoing molestation, or anything like that. Your husband's predilections are worrisome--and to you scary for sure and I think rightly so--but not proof. These sites get many views, perhaps millions, and only a small fraction of the viewers are actually pursuing these activities in real life. They are expressing fantasies for most of the people addicted to them. But you have the daughter's behavior that could be explained by ongoing trauma.
That is the wild card here and is more definite:
Something is very wrong, indeed. You are intelligent and you can see this. You need not question yourself about this. We don't know if it is developmental, true. It could be something in the Asperger Syndrome type of spectrum, untreated and thus her "hit and miss" rules of life that she follows. Or, it could be neglect as you also suspect, though my training and experience doesn't quite support that so much. Neglected kids don't give that kind of cluelessness that you describe.
However, ongoing molestation and abuse do support the description you provide. That I have to tell you is a concern. So, you have two leading possibilities in terms of her situation: a developmental problem or PTSD with neglect.
So I've confirmed that your fears are not outlandish; now what?
I don't know if you want to take a trip to visit your family and think things through about your future in this family. I would certainly support your not making her problems your duty or responsibility.
You may want to schedule such a trip and before the trip schedule a heart to heart talk with him, confronting him with what you know about his sexual proclivities and how they make you feel. Not being accusatory, but being frank. And your concern that his daughter is seriously in need of intensive mental health care and you're not sensing he recognizes this. You are welcome to show my answer to him to confirm this. Then after the discussion you will have time away to consider your next moves.
Okay, I wish you the very best!
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