。
She could no longer bear the insult.
Literal
[topic-は] no-longer that insult [contrast-に-は] could-not-endure.
侮辱 ('insult') is a Sino-Japanese compound noun, more weighty than the colloquial 悪口 ('bad-mouthing, trash talk'). The pattern には combines the targeting に (the insult is what she was enduring) with the contrastive は ('that one in particular,' implicitly contrasted with whatever else she might have been able to bear). 耐えられなかった is the negative past potential of 耐える ('to endure') — 'was unable to endure.'