Please do NOT respond to her -- ESPECIALLY if it's in writing (e-mail or text message) -- without checking with us first.
This is your moment of maximum leverage. You have her backed into a corner, she's going to get with OM immediately (I'm sure she called him within FIVE SECONDS of getting off the phone with you), and they are going to plan their strategy. You can be 100% assured that what she says (or does) to you next will be a part of this strategy -- THEIR strategy -- and not any true remorse or contrition on her part.
Not sure if you've ever wrestled, but you just got two points for a reversal. YOU ARE ON TOP NOW, and in control.