Livia is not the least surprised by her soon-to-be ex-husband's reply. The old adage does say that a woman does not ask questions unless she already knows the answers. Like all sayings, it is not always true, but this time it is.
What she is surprised by, however, is his lack of elaboration and justification. He does not explain why he did it. He is sparing her the sordid details too—details that she is dying to know but will also make her feel like dying if she does know.
He is giving her a simple admission of his wrongdoing and no more.
"Is that all you're going to say?" she prompts.
Raylen sighs. "If you have more questions, ask away. I will answer them. But I do not see a point in explaining myself when you have not asked for it. I cannot explain myself without sounding like I am finding excuses for my behaviour."