What kind of woman voluntarily stays in that death cult? Or raises her children in it?
She had already filed for a divorce and had a protective order against him.
There is no leaving of Islam, voluntary or otherwise. To try means that anyone can kill you. But you probably know that. Wives belong to husbands, and so do children.
To even try shows just how desperate this poor woman must have been. And of course, under sharia, the children belong to him totally.
He beheaded her because she filed for divorce and had a protection order against him.