At some level, he knew it was possible given the state of things, that she could come back. He'd known and recognized that since New Year's Day. Seeing her, as mad as ever, wasn't quite the shock it should have been. What shook him, and brought home just how evil the woman was, well that was the child she had killed. A child who had done nothing to her, but he'd long realized that killing and torture was life's blood to her.
There was too much to do, to worry about himself or his own feelings. A quick glance showed him that Hugo was taking care of Lily. And the Aurors had things under control at this point. He'd need to see to the rest of the students.