Actually, the original 13 states ratified(i.e, approved) the Constitution in state legislatures. They created a federal government. They needed no approval from Congress SINCE CONGRESS NEVER APPROVED THEIR STATEHOOD.
Thus, VA, NC, SC, GA broke no law when they seceeded. Likewise, TX was free to seceed having been unique among the states as a republic prior to staehood.
SCOTUS disagreed with your assessment.
Actually one one state was ever a true sovereign...and it sure as hell wasn't Texas, which was a spiteful bastard child of a state from the day it was conceived.