I don't agree on this one. I don't think it needs to be public for it to be sincere. Now if she has any desire to repair her reputation and not just slink away into the ooze, the a public apology would be a good start. But if it's just this one thing that needs to be made good for her to go on, then it's not necessary that it be done here.
I'm not sure she's got the stones to admit to it and apologize to it in public.