Complex sentence: Upon her arrival at Tutbury, the tall and beautiful 26 year old Queen of Scotland would remain in the custody of Bess and her husband for 15 years, and her presence would not only destroy Bess's marriage but destabilize the reign of Elizabeth herself.
Split into simpler sentences: Upon her arrival at Tutbury, the tall and beautiful 26 year old Queen of Scotland would remain in the custody of Bess and her husband for 15 years. Her presence would not only destroy Bess's marriage but destabilize the reign of Elizabeth herself.