A man followed the way of the devil until he lured him into committing incest with his little daughter. He did not have full sexual intercourse with her (no penetration occurred), but he merely rubbed the tip of his penis over her vagina and anus (no vaginal or anal penetration took place). If this man wants to repent to Allaah, the Exalted, what should he do? Should he conceal this matter or should he, or someone who knows about this issue, report it and refer it to the concerned authorities? If he should conceal his sin and repent to Allaah, the Exalted, what should he do with his wife, the daughter's mother? Is she considered divorced because of this superficial sexual enjoyment? What should he do with regards to himself, his daughter, and his wife?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

When the devil and the person's evil-enjoining self-lure him into committing such a sin, this indicates his weak faith, lack of chivalry, and the corruption of his human disposition; he is primarily required to turn to Allaah, the Exalted, in sincere repentance. It is forbidden to disclose this unlawful act to anyone. Instead, he should conceal it from all people. As for his wife, she is not considered unlawful to him as a result of his wrongdoing. Doing something unlawful does not render the lawful prohibited. Moreover, that which is forbidden by the Sharee'ah, it is as if it does not exist. Imaam Ash-Shaafi‘i said, "If a man had sinful sexual intercourse with his mother-in-law, his wife is not considered unlawful to him." [Al-Umm]

The famous opinion of the Maaliki scholars suggests that when the father  deliberately derives sexual pleasure with his daughter, then his wife, the daughter's mother, is not considered unlawful to him. Al-Kharashi said:

"Muslim scholars held different opinions regarding the father who intentionally derives sexual pleasure with his daughter (whether the daughter's mother becomes unlawful to the father or not) … The same as the difference of opinion regarding the ruling of the father who commits incest with his daughter. The opinion that they adopt is that committing adultery does not render what is lawful prohibited, just like the Shaafi‘is believed." [Sharh Khaleel] 

Allaah Knows best.