Is the wife considered divorced if the husband stipulated knowing who assaulted her in her childhood, and she only told him months later?

The questioner must avoid embarrassing his wife with such matters, which could lead to problems. As for his suspension of his wife's divorce, the matter depends on his intention at the time of suspension.

If he suspended the divorce on her not informing him immediately or within a specific time (such as a week), and she did not inform him until the specified time, according to his intention, then the divorce has occurred according to the majority of scholars. He may revoke the divorce before her waiting period (iddah) is complete, as long as this divorce does not complete the third divorce.

However, if his intention was to threaten and not to divorce, then he must offer expiation for an oath (kaffarat yameen) according to Shaykh al-Islam Ibn Taymiyyah.

And if he did not specify a particular time for her to inform him, then the divorce does not occur due to her delay in informing him, based on the understanding that the particle "إذا" (if/when) indicates delay (tarakhi). This is one of the opinions of the people of knowledge, and it is supported by the principle of the marriage remaining valid.