Let's say for example that your mother-in-law is a nudge, always with the remarks and the rolling of the eyes. Now, there's nothin you can say to her directly,that only makes it worse. If you've ever tried it, you know what I'm talking about. If you haven't please don't, save yourself the trouble. By the rules, however, you may talk to your husband about it,assuming you and he have really made a new family together in which case he cannot fault you. Of course there are ways to put it, some better than others. I don't recommend you saying Yknow something your mother is the burr on my ass. THis will not go over well. It won't kill you to use a little class. Anyhow, you know he's going to be aggravated, he worships his mother, as he should, but still, he's got to step in if you ask. If you decide not to speak to him, and keep it bottled up, because you don't want to rock the boat, the boat will rock none the less from your shaking with repressed agita every time she gets on your nerves, and you either get an ulcer, or throw a plate at her head. Then you will be the bad guy.
PS- If you speak to him with respect, and he tells you, that's my mother, watch it, you have a bigger problem, which may be what she's trying to tell you, in her own way. But in that case, better to know where you stand, sooner rather than later.