This story of the jealous stepmother is also included in the legend of Saint Juthwara (f.d. July 1), who is supposed to be Sidwell's sister. There is reason to believe that this legend is entirely mythical; although Sidwell is a real saint.
Born at Exeter, she was killed by her stepmother inciting the reapers to behead her. She was buried outside the city, where by her merits God heals the sick.
Lives kindly supplied by:
For All the Saints:
http://www.saintpatrickdc.org/ss/saint_a.shtml
An Alphabetical Index of the Saints of the West
http://www.orthodoxengland.org.uk/saintsa.htm
These Lives are archived at:
http://groups.yahoo.com/group/celt-saints/