I recommend the following books: "The Guru Papers" and "Karma Cola".
] has a new article as well from a conservative Christian perspective.
I was in a group that wasn't Kundalini based. I liked the exercise and was drawn to the carrot of "enlightenment". The group was proud of their authentic Hindu and Indian roots. They also seemed to have a hidden agenda. It became an all or nothing, black and white situation. I left. I didn't want mandatory statue god worship. It took the group awhile to reveal the statue part to me. It all came on slowly.
I know a Yogi Bhajan 3HO Kundalini follower. She wears a ring on her wedding finger for him and is completly under mileau control. Where she lives, what she does, what she reads, is all under the 3HO group control.
Yoga by itself is not a cult. Christianity by itself is not a cult. It is only when it is layered with a hidden agenda and the other Singer Criteria for cults that it becomes destructive. I thought yoga was really wonderful and slowly I began to
get myself into an all or nothing situation. Then I left. Thank God.
If your ex wants to go really deep into the group, she would probably like for you to assume more child care so that she can take more workshops, retreats etc.
I feel for you. Honor your child's feelings. Children know when something is weird. They go to other friend's homes and see things are different from their own home. Confirm your child's thoughts and feeelings.
I don't know what else to say. I say a prayer for you, your child and your ex.