I would just hang back and be there for Mom. Live your life, talk to her about withholding judgment of you but to be careful of them.
The above books are good and my favorite was The Subtle Power of Spiritual Abuse.
Mom sounds a little lonely and scared. does she have other friends outside of TWI? Maybe a new network --not a --your all screwed up intervention to meet new friends, but ...going to a new place for maybe volunteering or an actual church (might be to crazy) Sounds mostly like she needs some self-esteem to develop intrinsically from an external activity (kind of like validation without way people doing it, but just for who she is? make sense?)
BTW - I worked on that auditorium for free too....I swept all the trash up for what seemed like forever. (that and the dish room)