She wasnʼt mad at her brother for what he said and did at the rehearsal. Though part of her wondered how much of his anger was his and how much was Chrysalisʼ mind control, she still understood that he had a lot going on at the time. Maintaining the shield constantly, preparing for an imminent threat and getting married all at once must not have been easy. Seeing his sister accuse his fiancée of evil mustʼve been the final straw. None of this excuses his actions, but it justifies them, and that makes it easier to forgive. 