Is the questioner considered unjust to his children if he divorces his first wife due to continuous problems and her disrespect, despite the intervention of her family and her attempts to emulate her mother's behavior with her father, knowing that he has married another and seeks to preserve the children?

If the wife is disobedient (nashiz), the husband must follow the Sharia-prescribed steps to remedy her behavior. Divorce is not the first step, but rather the last. He must be patient, try to reform her, and supplicate for her guidance. If divorce becomes necessary due to the wife's harm and bad character, it is not an injustice to the children as long as the father fulfills their rights of maintenance and care. He must exercise wisdom in dealing with them to avoid negative consequences.