It's foolish to impute post-hoc arguments like that. There is no way either side could anticipate the number of casualties or the degree of destruction the war would bring. But the responsibility for those losses must lie with hose who initiated and perpetuated the conflict. I notice that you don't include the responsible parties in your condemnation. Pity that.
The responsible parties are those in the north who in their hubris and greed conducted an offensive war against the CSA. They just couldn’t believe that the people in the South were serious about separation and were willing to kill hundreds of thousands to make their point and reap the financial rewards that accrued to a tiny sliver of the northern population. The blood is on the hands of the Yankees that were determined they were going to keep control of their cash cow. So do you think conquering the CSA was worth the casualty count and the destruction and the general corruption that came with it?