From the first shot at Sumter, it was only a matter of time before the Union won.
Not true at all. Not one bit. At that point in time the war was not the 'Total War' that it later became. The confederacy was counting on many things at the start to offset the obvious numerical, logistic and technological superiority of the Federal Army. Such as:

1. The soldiers of the South having a vastly superior 'heart' for the fight. This was not an unjust assumption at all. It's a LOT easier to convince a man to pick up a rifle and fight for their freedom from an invading army (that's the south) than to pick up a weapon, and go into somebody else's land to subdue them (that's the north). Speaks volumes about Lincoln's command of that situation that was able to convince so many to risk their lives to re-forge the union. Granted, the Federal soldiers fought that war for many different reasons. But it always astonished me how much the northern folks sacrificed in that war. Would have been far easier to say 'let them go'.
2. The soldiers and politicians of the North would not tolerate a lot of casualties, and if the South fought a purely defensive campaign, they could inflict a great deal of damage, and bleed out the North's resolve to fight the war. Also not an unjust assumption. In battle after battle the South followed this strategy, and resentment against the war in the North increased. It was simply never enough to force Lincoln, or his generals, or the people to give up the fight. No way for the Confederates to know that at the start. After Shiloh, it should have sobered them up something fierce. But both sides blood was up by then.
3. The intervention of the European powers. Britain and France were huge consumers of Southern cotton, tobacco, and the like. The Civil War (after a time) would become a severe economic problem for those powers, and both sides knew that. It was up to the South to achieve military victories in the field, to build a reputation on which they could court European intervention that would bring the war to and end, while leaving the South and independent nation. Even under poor leadership, the North was able to succeed enough to convince the European powers to stay out of it. No way for the South to know that at the start.
   Hope of victory on these grounds was a possibility up until the summer/autumn of 64' when Grant fought his way (at unbelievable cost) to the siege works around Petersburg, the supply sources in the Shenandoah Valley were destroyed, and Sherman had taken Atlanta (a critically vital city for the Confederacy). That was the moment when the writing was fully on the wall. Federal resolve had been thoroughly demonstrated, and they should have known they were NOT going to break Lincoln's will to win the war, if they hadn't already done so. The numerical and logistical advantages of the north were still there, and were in fact increasing with the mass induction of black soldiers in the North, and the constant influx of immigrants from Europe to Northern ports. If Europe hadn't joined the war (militarily or diplomatically) when the war was going well for the Confederacy, they surely weren't going to in the Autumn of 1864. It was over. I revere General Lee has a solid tactician and an absolutely remarkable leader. But I also place the blood of all those (North and South) that died after Atlanta was taken squarely on his hands. There was no way for him to win after that point, but for whatever reason (probably many reasons) he refused to give up the fight until almost a year later. That was wrong.

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Which election are you referring to, jaystarstar? The presidential elections were in 1860 and 1864, not 1862.

The election was still pretty much in doubt in September 1862, and if Sherman had encountered problems or delays in taking Atlanta, it was conceivable McClellan could have won the election and he would almost certainly have called off the war and negotiated a settlement with the CSA.
Once Sherman took Atlanta, public opinion swung big in the North and Lincoln rolled to reelection. It was obvious Lincoln would accept no partial settlement of the war.

4. You ever seen Superman $#$# his pants? Case closed.

Actually, the simultaneous Union victories at Gettysburg in the east (July 1-3, 1863) and the surrender of Vicksburg in the west (July 4, 1863) are generally regarded by historians as the "high water mark" and turning point of the war that made the overall Union victory inevitable. Of the two, although Gettysburg was very important and got more of the press since it was much closer to the large eastern cities, Vicksburg was the more vital strategic victory in the Union's plan of encirclement and strangulation of the South. With rare exception, from July of '63 onward it was all downhill for the Confederacy.

Once Atlanta fell in fall 1864 and Sherman cut the Confederacy in half with the march to the sea in December, it was only a matter of time before the Union won.

4. You ever seen Superman $#$# his pants? Case closed.

It didn't say the Civil War ended in 1864. It said Atlanta fell in 1864 and referred to Isabella's hopes of compensation being dashed with it.
Didn't say the war ended.
"What happens to a dream deferred?"