Hi Jules.
I may be wrong, but the wording in your original post makes me think you're
almost condoning what your husband said.
You actually state that you made a "mistake" in sighing. And by not speaking out there and then after he passed that insensitive comment, I worry slightly that you may have given his remarks some justification, at least in your husband's mind.
I think you really should call him out on it, and ask for an apology. And if he
genuinely meant what he said, ask him to suggest an alternative to the current work/life arrangement. But my guess is that he's absolutely loving the fact that you are at home to nurture and bring up your children, and that he is happy that the two of you have the choice to be able to live as you do now - I'd imagine that in the majority of families with young kids, both parents have no choice but for both of them to work.
And you should never, under
any circumstances, be made to feel that your opinions or feelings, however you choose to express them, are a 'mistake'.