Complex sentence: For her own safety, Basina, was sent to the Abbey of the Holy Cross at Poitiers, but not before she was raped by Fredegund's soldiers, by which she lost both her honor and her inheritance.
Split into simpler sentences: For her own safety, Basina, was sent to the Abbey of the Holy Cross at Poitiers. Before that, however, she was raped by Fredegund's soldiers, by which she lost both her honor and her inheritance.