I think for reasons of drama, she must know that her husband was a bad guy. Yes, you could have it that she doesn’t. The thing to watch out for there is why you’ve made this decision.
Deciding that doesn’t know allows you to have a simple character. Though, then you have to figure out why she sticks around once she finds out the truth.
Deciding that she does know but has stuck around – this means you have a mountain of work on your plate. That character is complex, hard to sympathize with, illogical… all the sorts of things that make writing hard, full of false starts, inconsistent at first, and you’ll probably end up bald or grey. But this character is worth spending our time with.