It seemed as if she had become insane but it was only a way of surviving an impossible situation.

insane 由前缀 in-（表示"不、非"）和词根 sane（"神志清醒的"）组成，字面意思是"不理智的"。这个词指"精神错乱的、疯狂的"，形容人完全失去理智的状态。