One of the many tragedies of the Civil War is that the Secession Crisis that precipitated it was completely unnecessary.
If southern representatives and senators had remained in their seats in Congress, they could have blocked any legislation they feared with the help of Northern Democrats. They would have quickly realized that no, Lincoln wasn’t going to take away their slaves, put them in jail and have their slaves and carpet baggers from the North running things in their states. Lincoln had pledged not to interfere with slavery in the states, and, absent a war, he lacked the power to do so. Secession was a completely over the top reaction to the election of Lincoln, and, like many over the top reactions, it ultimately brought about what was feared.
Lincoln even supported an amendment to enshrine slavery in the Constitution if that would mollify the South. The amendment passed Congress and was ratified by three states before it became a dead issue due to the ongoing war. That such an amendment passed the Congress without most Southern senators and representatives being present is a clear indication of how willing Northern Democrats and many Republicans were to allay the fears of the South. Northern Democrats would have been happy to join Southern members of Congress in bottling up Republican legislation. After four frustrating years Lincoln would probably have joined the long list of one term Presidents which was the norm after Andrew Jackson. The South had absolutely nothing to fear from Lincoln. Instead, Southern fire-eaters stampeded more moderate colleagues to secede from the Union by portraying Lincoln as a mortal threat to slavery. It was the secessionists, by provoking a war they were bound to lose, who signed the death knell of slavery. God must have enjoyed the rich irony.