Where did you get that information about Lee and Whipping post from?
It was from the testimony of the slaves at Arlington.
http://civilwartalk.com/threads/r-e-lee-and-beaten-slaves.14363/
News paper articles posted before the rebellion.
http://joeryancivilwar.com/Civil-War-Subjects/General-Lee-Slaves/General-Lee-Family-Slaves.html
http://www.sonofthesouth.net/leefoundation/lees%20slave.htm
http://civilwartalk.com/threads/r-e-lee-and-beaten-slaves.14363/page-27
http://leepapers.blogspot.com/
An analysis of pro-Lee writing based on access to his slave legers.