Quote Originally Posted by EdwinLi View Post
From a certain point of view it will appear she kept it all a secret from everyone in Acient times but as Venat said, she had gathered people she could trust during the time between Elpis and the Sundering day. The issue is that we did not see her journey between Elpis to the Sundering day so it looked like she kept it a secret from everyone when she did not since she said before WoL left she went on gather allies she knows won't try to stop her plans to defeat Meteion.
Dialog from the Anamnesis Anyder cutscene:

Diplomatic Ancient One: Venat, please... Why must it be you? If I may speak plainly, I would sooner it were another... any other. You are our leader. None can take your place.
Venat: You know as well as I that but few support our cause. Far fewer than they who place their faith in Zodiark. If Hydaelyn is to stand a chance of opposing Him, I am the only one who might suffice as Her heart. Rest assured, however, I shall not vanish from this world. The form I take shall ever remain my choice.
Diplomatic Ancient One: Then I will press you no more. Only know this... you will be sorely missed. I wonder... is this how the Convocation felt about Elidibus?

This sounds to me like those closest to her were were oblivious to the sundering, so whatever she did tell them didn't seem to include the destruction of their civilization as they knew it. I doubt she'd have any followers if she had.