Is your daughter in IC? If not you should consider that. Talk to the counselor and explain that you feel XW is poisoning her and see what he/ she can do to help your D process those emotions. It needs to be an independent 3rd party, if you try to argue with D over every thing XW tells her then you're lowering yourself to XW's level and just confusing D. If you try to talk to XW about it I think it'll just be a waste of time. She will either insist she's right or she'll call you paranoid or both.
