In 2011, a historian published an eye-opening article in Salon about this issue. As Lee is trending on twitter, it is useful to re-read the article, here. Speaking to a historian, one of Lee's descendants said, “We are never, I repeat, never, going to let those papers out of the family. They are safe in a bank vault. I don’t even have them here. No one is ever going to see them.” Another example in the essay: One of Lee's wife's ( Mary Anna Randolph Custis Lee) reminiscences was accidentally seen by Lee scholar, Thomas L. Connelly, in 1977 which gave evidence to her hatred of Lincoln and Northerners, giving at the time new evidence for the bitterness towards the north that Lee's family held after the war.

Also, I want to point out that there are lots of flaws in Lee's military leadership - he was not a good manager or developer of talent, sending weaker subordinates West and relying on Jackson and Longstreet to a fault. He valued loyalty of Stuart over discipline, leading to Stuart abandoning Lee for glory before Gettysburg. He was also hampered by physical weakness after having understudied cardiac trouble in 1863 and after. He did poorly in West Virginia in 1861 leading to the split of the state and significant strategic advantage for the North (imagine how much weaker Union support would have been in Kentucky and East Tennessee if neighboring West Virginia were held by Confederates). And, of course, he was a violent racist.