Aw, Skinnycow, there's no reason why you can't do things that you enjoy. Sure, you do for your family but surely they can understand that mom/wife is human and has basic human needs.
It's bad when marriage begins to feel like a prison. I felt that way when I first got married because my life had changed so dramatically. I had new responsibilities and wanted my old life back. But now, I've realized that there really isn't any reason why I can't do what I enjoy. As long as it's not destructive, there should be no problem.
If hubby truly loves you, then he would want what's best for you and your family. Like the others said, a happy wife and mother, helps make everyone else happy. When you feel miserable, it's very easy to pass that misery onward. People can feel and see it.
So we're encouraging you to go for it! Do something you've been wanting to do for a long time. Let us know how things come about :)