WOW. I just read this thread for the first time today. What a mess. How far away is the wedding?

I agree with several others that your daughter is torn. Her loyalties are with her future husband now and the more that she sees the families torn apart, the more likely she is to move closer to his side. This is tragic.

It sounds like your daughter is caught up in the now - can't see the forest for the trees - and has forgotten what it is she wants for herself and her future. Is there anyway that you (or someone a bit removed from the situation) could try and illicit (?) from her what it is she wants life to look like in the future? Maybe then she could see how this marriage fits or doesn't fit with that bigger picture.

God bless you, your husband and your daughter.