If you only confess the parts they already know, that’s not honesty. It’s damage control.

Admitting the discovered portion feels like openness and works as containment. You get the credit for coming forward while the part that would actually change their view stays where it is, and if it surfaces later, the earlier admission becomes proof that you were managing them. Partial honesty often costs more than silence would have.

Work out what they do not know yet, and decide whether you are going to say it. If you are, say it in the same conversation rather than in a second one next week. One hard conversation is survivable; a series of them wears a relationship out.