What is the ruling on a wife seeing her husband’s private messages that indicate his previous and ongoing illicit relationships, and is she sinful for doing so? What is the ruling on her remaining his wife after she has learned of his adultery, his insistence upon it, and his desire to travel to his mistress? And is she obliged to inform him of what she has found out about him, knowing his rejection of advice and his tendency to create problems?

Spying on one's husband is forbidden, except in certain specific circumstances. If you intentionally spied, you have sinned, and repentance is obligatory. If you did not intend to spy, there is no blame. Your continued presence with your husband is permissible even if it is proven that he was not chaste when you married him, as the marriage of a transgressor is valid.

You must advise your husband. If you see that he persists in his wrongdoing and will only desist if you inform him of what you have discovered, or if you inform someone who can advise him, then do so. Be patient and use wisdom with him, so perhaps Allah will grant him repentance.