Kate was speechless at Erin's accusations because she knew that her sister was not making it up, she knew that most of what Erin had said was true.
She was the one who caused their parents' divorce. She always carried the guilt that she was the one who ruined her family, and she knew that Erin would forever resent her for it.
"If only I could turn back time and—" Kate stopped herself from completing the sentence before she said something she'd regret. She shook her head and said, "No, he deserves it, and Mom deserves better than my Dad. I did the right thing back then."
Kate wasn't sure as well, her tone still questioning what she did all those years ago. All she knew was that she always believed that what she did was right, even at the cost of ruining his perfect family man image.
Kate felt lightheaded after Erin left her apartment. It was the combination of both physical and mental exhaustion due to all the events of the day plus she was pregnant.
