As a therapist I need you to know that "trauma dumping" is not a clinical term. We made it up to describe the act of confiding in people who care about you. Which we used to just call talking to your friends.

As long as you ask if it's a good time, avoid unnecessarily graphic details, read the room if they're going through it too, and return the favor when it's their turn, it's not trauma dumping. It's friendship.