Just my opinion, but I didn't get the vibe that Dona was taking the response personally. I just thought she was arguing her point, or, as in a debate/discussion, supporting her argument.

But back to Kay: She may have been a "nagging bitchy wife" from the 1950s husband's perspective. But, by asking questions, Kay was doing something unheard of for the times; and that made her a brave, forward-thinking woman of some backbone for that era. From a general perspective, she merits compliments too -- not just brickbats.

There was one point about which Michael himself gave Kay the right to know: the progress of his "legitimacy plan," which he broached when he proposed to her. He made it a point of trust to tell her that the Family business would be legitimate in five years. It was the only aspect of his business, in fact, that he would tell her. So her reminding him that "it's been seven years" is the one time where Michael -- and we the audience -- can't fault her. In fact, when she does mention it, he does not react with anger as he did at the end of GF1, but instead he gently tells her, "I'm trying."
Yes, Michael wanted Kay to keep her place and mind her business instead of his. But I also got the impression by GF2 that just maybe, deep down inside, he needed her to question him once in a while, which is why he appeared more guilty than angry when Kay shot him that stinging look after the Tahoe shooting. Someone wrote on these boards a while back that Kay was Michael's conscience. Maybe he kind of expected her to keep him on track as far as going legitimate was concerned, to remind him of that goal (although I'm well aware that his own power mongering was the real impediment there).