River Donaghey grew up in a cult. Or at least that’s what some people called it. His parents called it a “personal-growth seminar group.” Its leader called it “one big happy family.” But there was a dark side to the world River grew up in. One he never heard about as a kid.  In the 1970s and 80s, a self-help company called Lifespring took America by storm. Hundreds of thousands of people walked out of Lifespring as true believers, convinced that the seminars had the power to change the world. But dozens of trainees claimed that after taking a seminar, they had a...