[ Now she feels even worse because concealing important facts for safety reasons is the entire reason she is who she is. Magical abilities and the secrecy surrounding them are her life story: past, future, and present.

Well. Sort of. Rei knows now, and Rei trusts her. So she returns the smile because that's what's important. Feeling sorry for herself can wait. ]

I understand. And - Rei?

[ Here comes the hard part. ]

I... I trust you too, you know? You haven't told anyone about my secret, and - for that? I'm grateful.

...But I'm also sorry. Really, Rei, I - I'm so sorry for what happened out there. About the way I was acting? You could've gotten hurt and I wouldn't have cared at all.