When you look at objectively, Katherine took a personal matter between herself and GW and used it as an excuse to manipulate and insult a lot of people, including long time friends.
She decided the best way to get back at GW was to become the sort of person that he (and she) hates. During the times she slips back to her real self she shows as much disdain for the Governor and Douglas as he does. Yet, she's perfectly willing to flirt and cozy up to to Cuthbert to make GW angry and make the governor think he has a shot. With Douglas, she encourages his interest in Becky knowing full well her father would never approve a marriage and knowing he's like his father whom she clearly has no use for. She also encourages her daughter to play the same games.
She insults long time friends Birnbaum and Drago simply because they are also GW's friends and it fits in with her act. She was also unreasonably rude to Mrs. Warren, but that at least could be due to what she believes in GW's history which, admittedly he never denied.
That's why, in my opinion, she deserved her comeuppance. She brought others, including her own daughter into a fight she was having with her husband. It was mean, manipulative and dishonest.
When we get glimpses into her true personality from her "slips" and the stories told by GW and Birnbaum, we get a glimpse of a really strong, brave, and loving person. Had she behaved in character from the beginning (i.e. 2 years before the events of the film), it might not have saved her marriage, but she at least would have been more respectful of the people around her.