It is a cult. And sometimes it takes people twenty or thirty years to realize that and that is not uncommon. You were told never to talk about the group outside the group. Well, now you can! If you look at all the cult literature, you will see that it fits all the descriptions.
It's probably worth repeating this here:
Ten warning signs of a potentially unsafe group/leader.
Forum: "Cults," Sects, and "New Religious Movements"