Agree with previous posters. Be open about your concerns. Fight to keep an equal position as a parent in having a say regarding your children's upbringing. Definitely no home schooling. Encourage your children to participate in sports and extra curricular activities. If your husband is intransigent then you fight hard. If the fight seems futile then you go to the separation part, but making sure that your kids understand clearly that you have their best interest in mind. I am in a similar situation to yours, but I have the big advantage given by the God of the Bible, I am a male. I know, it sucks being a smart woman and an independent thinker in a Christian cult.
You definitely have your brain and heart in the right places. You just have to proceed slowly and carefully.