。
She could not bear the insult.
Literal
She [topic-は] that insult [contrast-に-は] couldn't-endure.
耐える ('to endure, bear') takes its target with に, not を — a worth-memorizing irregularity. The compound には here stacks the topic-marker は onto the に, sharpening the focus: 'as for that particular insult.' Combined with the negative potential (耐えられなかった = couldn't endure), the construction emphasizes that this specific thing crossed her threshold of tolerance, even if she could endure other things. 侮辱 is a strong word — it covers anything from a personal slight to a serious affront to honor.