Methinks thou dost protest too much! And here for your consumption and digestion are the articles that the South seceded under -
Amendment IX - The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.
Amendment X- 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 the people.
So the Constitutional scholars and the Founders recognized that these two Amendments gave a state the right to secede, but your type seems to blithely ignore them. Like I said before, your Constitution is written in pencil for ease of revision.
Hardly. And nowhere does the Constitution give states the right to trample on the interests of other states or to secede without consent of all the parties involved. As many Constitutional scholars and Founders have said.