You may live in the north but you must have been educated in the South. ;-)
Hell, there are native Southerners that will argue that the War was fought over slavery. It's a testament to how PC the public schools have become.
In fact, I believe the states that wished to leave the Union had the Constitutional right to do so. They voluntarily joined the Union, so they had the right to leave if they wanted. Lincoln’s action starting the War Between the States to force them to remain in an association they no longer wished to be part of was unconstitutional and illegal.