While Aella’s post is very vivid in describing the horror of abuse, I don’t necessarily see it in your post. You don’t seem to be in a vulnerable/dependent position with respect to Carla and Dave, they don’t humiliate you, don’t make you doubt your own experience, don’t seem to discard your feelings, and so on.
That’s why if you said to me “I reserve the right to do X, if I find that you are manipulating me”, I wouldn’t be sure what you mean. (Even on the objective, God’s eye, level, let’s forget the question of how we make sure that it has indeed happened for a second).
Your friend’s case seems to be very clear cut, and the root issue is not some vague manipulation or secrecy, but the actual abuse that, I assume, continued through their interaction.