What are the consequences for a wife who uses government health insurance obtained by her husband through incorrect information, knowing that it is forbidden, especially concerning her children's expensive dental treatment, their school fees, and their free meals, and is it permissible for her to pay from her private money without her husband's knowledge, or to boycott him if he refuses to stop using this insurance?

May Allah reward you for your diligence in seeking what is lawful. What your husband is doing by deceiving to obtain government insurance is impermissible. If the husband insists on his stance, it is not permissible for you to use the insurance funds for yourself and your children except to the extent that the husband paid. You can financially assist the school with an amount that covers the cost of what was provided to them. As for the health insurance you have, it is unlawful if it is commercial, and it is not permissible to voluntarily subscribe to it. For someone who is compelled to subscribe, the sin is on whoever compelled them, but it is not permissible for them to take from it except to the extent they contributed.