Is this marriage valid, what is the ruling on a child born from adultery and how should he and the mother be dealt with after this act, is her brother’s action correct, and what is the ruling if he agrees to kill her?

A man is not permitted to marry a woman with whom he committed adultery while she is pregnant with his child, except after she gives birth, according to the majority of scholars. The child resulting from adultery is not attributed to the adulterer.

In contrast, some scholars, such as Al-Hasan Al-Basri, Urwah ibn Az-Zubayr, Sulaiman ibn Yasar, Muhammad ibn Sireen, Shaykh al-Islam Ibn Taymiyyah, and his student Ibn al-Qayyim, hold the view that such a marriage is valid and the child is attributed to the adulterer, provided the woman was not legally married to another man and no one disputed the child's lineage. Some also narrated from Abu Hanifa that he permitted marrying her while she is pregnant to provide her cover, and the child would be attributed to him.

In all cases, a child born out of wedlock has full children's rights and is not punished for the actions of his parents.

As for how to treat the woman, if she repents and becomes righteous, then repentance erases what came before it. If she persists in sin, she should be advised, commanded to do good, forbidden from evil, and prevented from the causes of sin.

The attempt to kill her by relatives is impermissible and forbidden. It is the killing of an innocent soul, and a great injustice and sin, especially if she is pregnant.