Well look at it another way. Since you believe that the southern acts of secession were legal, and that the confederacy was a legitimate, sovereign nation, then what prevented the western part of Virginia from seceding from Virginia and the confederacy and rejoining the Union?
Concerning the secession of West Virginia, I'll have to check the Confederate constitution to see what it says.
But according to Lincoln's own logic, and the US Constitution, it was CLEARLY unconstitutional-- yet Lincoln supported it.
Do you need me to look it up for you, or are you capable?