Someone is handing you a line here. The only way you could breathe out enough moisture to have it condense on the ceiling is if the room was the size of a closet and totally airtight.
If the moisture is really condensation then the humidity levels are high and that area is colder than the rest of the ceiling. Wet insulation doesn't provide any real insulating value so even if it's there it's bad. Either there is an air leak in that area making it colder or the problem isn't condensation. Maybe there's a water leak above that area? There is something going on and it's not your breathing!