They're not the only ones that have spewed hate, BLM was as bad or worse.

If we are to indeed learn from history, what better way could there be than reading the very words of two of the states that resulted in the Civil War?
DECLARATION OF CAUSES: February 2, 1861
A declaration of the causes which impel the State of Texas to secede from the Federal Union

"She was received as a commonwealth holding, maintaining and protecting the institution known as negro slavery--the servitude of the African to the white race within her limits--a relation that had existed from the first settlement of her wilderness by the white race, and which her people intended should exist in all future time. Her institutions and geographical position established the strongest ties between her and other slave-holding States of the confederacy."

"In all the non-slave-holding States, in violation of that good faith and comity which should exist between entirely distinct nations, the people have formed themselves into a great sectional party, now strong enough in numbers to control the affairs of each of those States, based upon the unnatural feeling of hostility to these Southern States and their beneficent and patriarchal system of African slavery, proclaiming the debasing doctrine of the equality of all men, irrespective of race or color--a doctrine at war with nature, in opposition to the experience of mankind, and in violation of the plainest revelations of the Divine Law. They demand the abolition of negro slavery throughout the confederacy, the recognition of political equality between the white and the negro races, and avow their determination to press on their crusade against us, so long as a negro slave remains in these States."

"That in this free government all white men are and of right ought to be entitled to equal civil and political rights; that the servitude of the African race, as existing in these States, is mutually beneficial to both bond and free, and is abundantly authorized and justified by the experience of mankind, and the revealed will of the Almighty Creator, as recognized by all Christian nations; while the destruction of the existing relations between the two races, as advocated by our sectional enemies, would bring inevitable calamities upon both and desolation upon the fifteen slave-holding States."
https://www.tsl.texas.gov/ref/abouttx/secession/2feb1861.html

A Declaration of the Immediate Causes which Induce and Justify the Secession of the State of Mississippi from the Federal Union
"Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth. These products are peculiar to the climate verging on the tropical regions, and by an imperious law of nature, none but the black race can bear exposure to the tropical sun. These products have become necessities of the world, and a blow at slavery is a blow at commerce and civilization. That blow has been long aimed at the institution, and was at the point of reaching its consummation. There was no choice left us but submission to the mandates of abolition, or a dissolution of the Union, whose principles had been subverted to work out our ruin."
https://www.civilwar.org/learn/primary-sources/declaration-causes-seceding-states

Justifying it does no good either. I do not think you were implying that but just to be clear both sides are wrong and will be a part off the next decade unfortunately.

At the time they were in the right. It was an industry that they depended on, the north didn't depend on it as much.