Complex sentence: His widow, Jane, Viscountess Rochford, continued to use the courtesy title until she, too, was attainted for treason and beheaded on Tower Hill on 13 February 1542 with Queen Katherine Howard, the King's fifth wife.
Split into simpler sentences: His widow, Jane, Viscountess Rochford, however, continued to use the title after her husband's death. Lady Rochford was herself attainted for treason and beheaded on Tower Hill on 13 February 1542 with Queen Katherine Howard, the King's fifth wife.