Batman waited, letting Damian study him. He got the impression the boy didn't believe him, which was curious.
Part of him wanted to question the identity of 'mother' but for now, he kept quiet. It would come out on it's own in time, and like the identity of his sire, Batman was only fooling himself to deny it. He could see it clearly.
Resisting the urge to comment on Talia's habit of being manipulative liar, and loyal only to her father, Batman simply replied, "I'm sure she did. But I didn't ask about me, I asked about you. How long have you been in Gotham? How did you get here? What were you looking for in the Cave and why didn't you come to me sooner?"