Complex sentence: The crisis caused the Emperor Nero to consider withdrawing all Roman forces from Britain, but Suetonius' eventual victory over Boudica confirmed Roman control of then either killed herself so she would not be captured, or fell ill and died.
Split into simpler sentences: The crisis caused the Emperor Nero to consider withdrawing all Roman forces from Britain, but Suetonius' eventual victory over Boudica confirmed Roman control of the province. Boudica then either killed herself so she would not be captured, or fell ill and died.