Complex sentence: Up until 1788, portraits of Charlotte often depict her in maternal poses with her children, and she looks young and contented; however, in that year her husband fell seriously ill and became temporarily insane.
Split into simpler sentences: Up until 1788, portraits of Charlotte often depict her in maternal poses with her children, and she looks young and contented. Levey, pp.7--8 However, in that year her husband fell seriously ill and became temporarily insane.