In the Name of Allah, Most Gracious, Most Merciful.

 

All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.

 

Sperm donation is not allowed in Islam as ruled by eminent jurists, including the World Council of Jurists. So, if your husband says he simply donated his sperm to help the girl cure a disease, it is not different than someone saying that he committed adultery with a woman to cure her of a certain disease.

 

However, he seems to contradict himself when he also says he married her. This does not help to render his action as valid as she denies it.

 

Therefore, there is no justification for sanctioning his action.

 

Allah Almighty knows best.