Teach critical thinking skills using other topics such as buying a house, a car and any other "important decisions" in life.
Maybe then watch some of the Leah Remini show from last season and this one also. If you do this with her and they say something that parallels the WTBTS method of controlling members watch her body language to see if she responds to anything. Had a relative about 10 years old say "Wow,.. the Sea Org is like Bethel"
Its a very slow process as you have to make sure you don't set off a trip wire driving them back in deeper. Know when to back off and arguing isn't the way to get a person out of a cult,.. aka High Control Group. Use the Socratic method by asking questions that she will have to answer, if not out loud, to her self.
Welcome,.. embrace the word Apostate as its not what you think it is as the WTBTS wanted us to understand it. Its meaning is "changing ones belief" or something like that. Jesus would have been an apostate to the Jewish system.
I tried to argue with my wife initially and could see I was doing more damage than good so spent the money and had a telephone interview with Steven Hassan to figure out the correct way to help a person out. Money well spent as my family of 4 are out now.