Hi Emery, it depends how well you know this person and their circumstances, but if you really care about them, tell them TTATT, and save them all the anguish they are going through right now.
Listen in a non-judgemental way, and compare to them the way they were treated with the way Jesus treated his followers, and then keep adding other inconsistencies of the organization to future conversations. I am sure you wont run out of them.
I hope they don’t come back, and that they can make a good life for themselves out of this abusive/hypocritical/insane cult. The same for you.