Lee loathed slavery (and that is a fact) through his own experience with it
"Loathe" is too strong a word. Lee wasn't happy about slavery, but he was able to live with it.
He thought it had work to do, civilizing the slaves, and that God would do away with it in his own good time.
Lee did refer to slavery as "a moral and political evil" in a private letter, but he felt that for the time being it was a necessary evil.
OK; I know that Lee was very worried that men were using female slaves as concubines and he warned his sons severely against this. He truly hated that men were abusing women and that the two races were intermingling. He was a man of his own time (like Lincoln) but to deny that he had a moral compass is just plain wrong.