I was with you until your last sentence, which is when you went off the rails. Talk about a non-sequitur! You go from discussing the Constitution and the consequences of secession — all valid points; but then, peculiarly, you veer off into the realm of irrelevance, and ask if Texas has nuclear weapons. As I said, a non-sequitur.
Maybe you were suggesting a nuclear war over a state seceding? I doubt even Russia would do that.
Now Russia was able to get Ukraine to return all of the nuclear weapons that were located within Ukraine. Ukraine itself has said they regret having given them back because they would have deterred Russia from invading if they had not given them back.
The same may apply if Texas has nuclear weapons located within their borders, as to whether it would be a peaceful or less than peaceful exit.