I think the best thing to do is to discuss it with your husband. If you speak to her directly about your disagreements it will cause serious problems. He is her son, so she is more likely to accept what he says. Try to stay calm. He should support you.
I am very lucky to have a wonderful mother in law. She is nice like my mum, and it helps me not to get homesick because i am close to my mum and my mother-in-law treats me like her daughter
hope you solve this problem. Good luck!