The secret is out, and the toothpaste is out of the tube.
toothpaste is out of the tube
idiomA situation that cannot be recovered or reversed back to its original state.
Origin
disputed originFrom the practical impossibility of getting toothpaste back into a tube once it is squirted out.
Once the company announced the merger to the public, the toothpaste was out of the tube and they could not go back.
The sensitive documents were leaked to the press, and like toothpaste out of the tube, the damage to the organization's reputation was irreversible.