Welcome Covert.
Talk to your wife and ask her why she has been abusive to you and the children? That she should go to the meetings herself if that's what she wants. That decision is up to her.
Google the JW pedophile problem. Their ridiculous 'two witness rule' that is needed to DF someone. Their years of telling a person to wait on Jah, discouraging even reporting the sexual abuse to the authorities......... leaving the child in danger of repeated sexual abuse.
That for the time being you don't want your children exposed to this problem. You want them to be educated, safe and well loved.
Edit to add: Good advice from others. Since I now understand that she has all of her family in you probably should not be too critical about their 'truth' or try to talk her out.
Do not agree to allow the children to be baptized tell her they need to grow up and make that decision later in life.