My mother in law is so bizarre. She always supports my husband even when it's obvious he's wrong and it makes me feel like the outsider in the family. It's very very frustrating and humiliating. What can I do?

Well, I would say that her behavior totally resonates with most of the MIL's worldwide. Instead of trying to get validation from your MIL, why does your husband not realize his mistakes by himself? I would work on that more than trying to get your opinions validated (that too from your MIL)