I really hate my mother in law. She gets jealous easily. She made such a big fuss and cried when my hubby gave me a gift for wedding anniversary. My hubby is at his wits end. We bring my in laws out regularly and buy things for her occasionally too. How do I tell her to grow up?

If she refuses to grow up, you do. The thing that you mentioned about her clearly indicates that she actually would not grow up and she is on some different wavelength altogether, and you would obviously get frustrated stooping to that level. I suggest, just ignore her and as long as your husband understand all this and knows that you are adjusting and managing, it should be cool with you. And if she pisses you off so much, have minimal outings with her. Less interaction would mean less issues. Also there is no need to tell her that goes between your husband and you if she makes so much of an issue out of it.