In-laws problem exist world wide. Let me suggest something. Have a meeting with you husband and his brother and his wife. Discuss the issue. They wont confront their parents because they wouldnt want to let them down. As long as your husband is ready to support you, you have nothing to worry about. Ignore your in-laws. Dont do what your mother in law doesnt like. Dont piss her off basically. If she says rubbish about you to your husband, make sure your husband knows she’s lying. Build that trust with your husband. No drastic step is going to change your mother-in-law. Ignorance is bliss. But make sure your husband supports you. Thats of utmost importance. As long as he knows his mother is lying there is nothing to worry about. He doesnt have to confront her. But he should fight with you because of his mother’s stories. And this is possible only with a strong trust and a heart to heart conversation.