I would assume that your reaction to her disclosure does not require an apology on your part. You were quiet, thoughtful; it caught you by surprise; it doesnt sound like you reacted inappropriately or harshly or hurtfully.

Also i wouldnt necessarily read anything into a change in tone or length of her emails - that could just depend on how much time and how many emails she has. If it is not an emergency, i would not email her again until i had seen her again.