Okay, I have seriously no idea why everyone is hating on the H. He's basically told his wife that he will do what she asks him to do in regards to his mother and tells Mother Dearest off every time she gets horrible - OP just hasn't come to a conclusion what she wants those boundaries to be yet (understandably). Why in the world is that his fault?! He's completely letting OP decide what she wants and is willing to enforce it based on what OP says. Let's be understanding of what a support that is in itself. From what I can tell, he's saying - "I know my mother is horrible to you and I hate that. Even though she is my mother, I will let you decide how much or little you want her in our lives and I'll abide by that decision and enforce it."
My advice to OP: you said your H can't stand being around her either - does she know this? Does she know that her little "baby" is extremely put off by her behavior? It's one thing for H to defend you, it may be a complete blow to her to realize that he hates being around her too.
Either way, props to your H for having your back. Sounds like you got a good one who really understands that you are his closest family now.
Edit: In regards to the "you know mom's a b***." comment at the wedding. What she did was horrible, there is no dispute here. But unless you guys made the decision to not invite her, she made it clear what kind of woman she was a lot earlier. Some people make the decision to invite people they don't like to their weddings for the sake of family or whatever - but that means they just have to deal with whatever stupid antics those people come up with. She was invited to the wedding, so there really isn't anything else you can do other than ignore her as best you can unless you really want to let her steal the show by getting in a fight with her. I can totally understand not wanting to fight that battle on my wedding day.