This sounds so much like my situation it's scary! I wish I could offer you advice on how to deal with this, but I am trying to figure out how to deal with my own very intrusive, controlling MIL as well. I served my husband with separation papers this past summer because our marriage was so full of problems for the last year and a half that seemingly couldn't be resolved....I felt at the time that his mother interfering with just about every aspect/decisions of our lives (from the small things, like 'recommending' what brand TV we buy, to 'offering' names for our soon to be born child, to 'guiding' us on our finances- ALL unsolicited, of course), was just part of the problem. We reconciled because he told me how he realized he needed to change (the behaviors that didn't involve his mother), and he has followed through. I have never during our marriage directly told him how much it bothered me that his Mom interferes....the interference occurs when he tells her what we are doing in our lives, and she in turn, has 'advice' (even when we've already made up our mind) because she basically wants us to live exactly the way she and her husband do (I basically don't care for their lifestyle, but I would never 'give advice' or 'recommend' to them how they should live....I want to live the way me and my husband want to live!). My husband respects his mother, so when she 'suggests' things, he starts to seriously consider them, which in turn, infuriates me because 98% of the time I don't like her ideas. Even though I thought this was only part of our marriage problems, I have come to the conclusion via time and introspection, that much of our problems, which were disagreements about major life decisions, stemmed from the 'suggestions' (read: interference) given by his Mom. I couldn't really see this at the time because he never would say 'My Mom says x,y,z, etc.....'. So even though the behaviors that were unrelated to his mother interfering have changed, the level of interference really hasn't. His mother told him after he told her he wanted things to work out between us and he was going to do whatever it took that he shouldn't go back to me and proceeded to insult where I am originally from (they are from CA, we live in NC). She also refused to talk to him for a few months after that when he would call her. What a piece of work!
Just know that you are not alone- I have amassed a ton of resentment for her all along, but especially recently.
I would recommend counseling- on your own at first, and then later with your husband if he is okay with it. I'm guessing he doesn't see how intrusive his mother is (mine really doesn't), and an independent party might be able to point this out to him. At least that is what I am hoping will happen with us in our marriage counseling when I mention this topic (we have other things to sort out first). Good luck!