Who knows what was in the heart of the commander of the confederate army? Or any of them, in fact, that fought to maintain the institution of chattel slavery in the united states? I doubt, if we could use a time machine and somehow interview the commander, officers and rank and file, that many of them would say they fought because of hate. I suspect that by and large the men in that army found their inspiration to take up arms and fight to the death for much more mundane "reasons" - much as the rank and file of soldiers do today.
They probably were told that they were fighting to keep the enemy from taking away their way of life. Their politicians and leaders - who were directly profiting from slave trade - probably told them they were fighting for "freedom", or "the American dream", or some other gosh golly notion. And oh yeah - they probably threw in some demonized descriptions of those damn Northerners, just to squeeze that last morsel of murderous patriotism out of them.
Just like the wars today that are really fought to expand empire or get cheaper petroleum, the civil war was fought to maintain the cheap industry of the slave business and all the wonderful affluence it afforded a relative few.
Was Robert E. Lee a hateful person? Why in the world would that make one **** of difference? Slavery was hateful. War is hateful.