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?

Like it or not, this is how it's going to be for most part of your life. Your husband is your MIL's child, it's obvious she will support him. But don't forget that you are his wife. Whether or not she takes his side, you can always go upto him and tell him where he is wrong. He has to spend the rest of his lief with you and not his mother, so there is likely chance you can slowly and gradually make him understand what hurts you and what you think is best for him. This solution implies even if you live with your in-laws. If you are open to your MIL, you can tell her how you feel.