She knows he does, and she wouldn't take it away from him. Not because of this.

"You should be. What were you thinking?"

She could probably make a pretty good guess, but she wants to hear it from him anyway. She can tell that he is genuinely remorseful, and that's a good start. She's not going to hold this over his head forever, she just needs to go over this a bit to get rid of the emotional chaos Tony's news and his letter caused.