What a tough choice!
For the best possibility of helping her, though, I would think that the more she sees you, does things with you and your family, the easier it would be for her to 'come back to you' and 'leave the Borg' if she 'woke up.' Right?
If I was "the mom", and my son kept close to me, talked with me even though "I returned to the evil", I wouldn't feel bad leaving WT in the future, and admitting it to my son, because he was always there for me as a friend, even though I had 'returned.'
If you don't lock her out, and then she blocks you (in the future) you won't have any question of "What if I had......?"
She might draw the line in the sand, who knows?
Until then, you have your best chance to help her out. She wants friends, she wants things to do. If something happens in the org, or to her to change her mind, you will be there.
On the other hand, I know how you feel when things are hypocritical. It's hard. I hate injustice too.
Personally, getting her involved in other things (hikes? bike rides? beach trips? lake? river? dancing? BBQs? going to the movies? a concert? playing games at your house, fun stuff) might help her see that "the Borg" is not the best way to have fun, and that there is life outside of the organization. Plus, she will have less indoctrination. (try to take her on a Sunday or a "Tuesday night", etc. )
Good luck, let us know
chaching
