Keep reading, the truth has been altered for political gain, you need books dating back to when the war started, there are old news papers still to be found. The hard truth is that the Confederacy never gave gave up being Americans. The war by law was illegal but the all knowing, all powerful central government didn't care.
In reality the Confederacy was inline with the writing of the Constitution. If you read the document you would understand that Lincoln abused his power and stated a unauthorized war.
Put your feelings aside and read. 
The Ninth Amendment stated, “The enumeration in the Constitution of certain rights shall not be construed to deny or disparage others retained by the people,” and the Tenth Amendment says, “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” These two amendments assured the states of continued autonomy in handling most of their internal affairs.
The war was never about slavery but it played its part but even if that was the only cause the war should have never happened. Look at it like this, if any state wanted to make all drugs legal, the people voted and it passed and in response congress declared war some of the other states would join together and fight. Just to be called traitors 160 years later by people to lazy or unable to follow the cause and effects.