This worry usually comes from picturing hypnosis like an interrogation where everything just spills out. It's actually the opposite: during the trance itself, you normally don't talk at all. That's because the subconscious doesn't communicate in words — any talking runs through the conscious mind, which is exactly what we're setting aside during hypnosis.
Whatever you do tell me in our conversation before or after is protected by professional confidentiality, the same as in any therapy. You decide how much you share — hypnosis itself doesn't "pull" anything out of you.