Make sure in your communication with your sons that you don't alienate their natural affection for her. They will resent you when they become men.
How can you possibly accomplish that? Teach them about cult personalities and control tactics used to create those personalities. All of the negative behaviors she displays should not be dismissed but they shouldn't be fully blamed or focused on either.
Placing blame directly where it belongs, on the cult, allows your sons to maintain a healthy love for her while learning and observing how destructive the cult is. May work for you as well.
Her true nature is still under there somewhere. Never give up hope it might break free one day.