What is the ruling regarding a man who married and had children, then it became clear that his wife is his paternal half-sister?

The marriage of a man to a woman from whom he has begotten children is annulled if it becomes clear that she is his paternal sister. The daughter is attributed to her father, because ignorance of the prohibited degree of relationship is considered a doubt that averts the hudud punishment, and every doubt that averts the hudud punishment establishes lineage.