Lily didn't react much to her sudden outburst, as she indeed did trick her. It was something she should have been proud off having tricked someone that powerful, and someone who has gained wisdom, after living for many, many years.
Yet she felt nothing, and the reason her being like that was because when she was going through her physical changes, memories of all her tamed 'beasts' assaulted her, without end. She had to endure, as they came all at once.