I know you want to give her the benefit of the doubt, but it sure does sound like she's using God to justify what she is doing to you and your family. Anyone can use God or faith in God to try and justify their actions. It doesn't mean it is a real and true faith or even search for faith. I hope she really is searching because, if she is listening to Him, she will know what she is doing is wrong. I hope that is the case. Continue to pray for her and for strength for yourself.