First and foremost, Cid, it was not a civil war. Get it right. There was no law that prevented succession. The South succeeded and became a separate nation. It was the War of Northern Aggression. The South did not invade the North until later in the war and it did so defensively. Bobby Lee could have and should have prosecuted his invasion of the North early on as eventually did. The war would have ended much sooner. The South lost and the North wrote the history, often incorrectly.
My great, great grandfather and my great, great uncles served under Maxcy Gregg in the 12th South Carolina Volunteer Infantry and fought in many of the big battles including the Wilderness and the Bloody Angle.
Slavery was wrong, though my family owned slaves. When my great, great grandfather left he freed his slaves and gave them the option of leaving or sharing in ownership of the farm. I'm not excusing his actions. It is what it is. My grandmother died when she was 107 and my great, great grandfather died when he was 92. I am fortunate that my family history was fairly current in that regard. I don't know how many slaves my family owned or how many elected to stay. I do know that two slaves, "Aunt Mandy" and "Uncle Ease" elected to stay and stayed throughout the war. They were given some of the land that belonged to my great, great grandfather. It wasn't worth much by then as Sherman's troops stole and burned damn near everything.
What would I do today? That is not a fair question as the zeitgeist of that time and now as so vastly different. Southern born and bred people - white and black - still today identify themselves by the Southern heritage above even their national heritage. Southern culture would not be what it is without black and white people. We share so many things in common. We would not be who we are without each other.
I do believe that had the South won the war slavery would have ended anyway, and that there wouldn't be the racism in the South that exists today.
The war was largely a war between two vastly different cultures and two distinct economies. Was slavery a factor? Yes, I believe it was. Was it the single reason? Was it the reason that the South continued the fight after such terrible and tragic losses? Was it the reason that Bobby Lee's army begged him to continue on after Gettysburg and Appomattox? No, it was not.