"I -- uh....." she couldn't just tell him. The words that Kate needed to explain it all wouldn't come, just remained stuck in her throat. A whole novel's worth of words buzzing in her head and stuffed in her mouth, waiting to be poured out.
It was ridiculous to let him go, to pull her hands away from his and take a step away, but she found she needed the distance. With Castle so close after the two of them had been apart for so long, it was a little hard to think straight. "I broke up our marriage," she said softly, her voice breaking on the last word as fresh tears clouded her eyes. "And it was stupid and I'm an idiot and I'm so, so, so sorry I did it, but I just -- some things happened and I was scared that you or Alexis or your mom would end up killed for something I did and I couldn't take that chance. I couldn't let someone hurt you because of me."