Please show me where it says the Supreme Court has either original or appellate jurisdiction in controversies pertaining to a State and one of its own Citizens.
-----
See Texas v. White.
I've seen it. The agreement was between White and the Sovereign State of Texas. It was not made while Texas was a member of the Union.
If, therefore, it is true that the State of Texas was not, at he time of filing this bill, or is not now, one of the United States, we have no jurisdiction of this suit, and it is our duty to dismiss it. [p720]
The court ASSUMED the question of jurisdiction in order to justify it's actions, and they answered their own assumption by saying Texas never had the right to leave.
Limits on the jurisdiction of the Supreme Court.
this resort must necessarily be deemed the last in relation to the authorities of the other departments of the government; not in relation to the rights of the parties to the constitutional compact, from which the judicial, as well as the other departments, hold their delegated trusts.
James Madison, Report on the Virginia Resolutions
By it's opinion that Texas never had the right to leave the Compact, the SC negated its own authority. True Law cannot contradict itself.
-----
Accordingly, state pretensions to unilaterally leave are unconstitutional, and void.
Please show me the part of the Constitution that prevents it.
The States unilaterally left the Articles of Confederation and PERPETUAL Union.
Not only is there nothing in the Constitution of the United States that bestows the authority you claim, there is a great deal of previous history that says otherwise.
If the right of secession didn’t exist, WHY was the House trying to come up with an amendment to the Constitution making a procedure for it?
Journal of the House of Representatives of the United States, 1860-1861
MONDAY, December 17, 1860 Page 82
Art. 8. Whenever a convention of delegates, chosen in any State by the people thereof, under the recommendation of its legislature, shall rescind and annul its ratification of this Constitution
-----
Accordingly, federal pretensions to judge a State's Right to unilaterally leave are unconstitutional, and void.
Texas, by pretending to secession, and committing insurrection, reverted to the status of a territory. It has no authority to alienate land or people from the US. All it could do was invalidate its state government, ruin a lot of property, and get a lot of people killed. Unfortunately, some of the wrong people got killed.