No, you're just entering your bubble again. If Texas seceded from the union, I don't think it would be debatable, they would be considered nutjobs.
Also, none of those USA allies would do business with Texas if the USA stressed the point. And if enemies of the USA started doing business with them, then there would be a military blockade preventing it.
There might even be some concerns of weapons of mass destruction, genocide, or some other reason to invade.
Again, this has already happened with Cuba. And they weren't even a state, plus were backed by the Soviet Union.