While it's true that Texas may have the legal right to secede, it's doubtful they would have the economic stability to survive such an act. Especially when the religious nuts who are trying to destroy the Texas Board of Education get the power to push the state back into the dark ages. Without the power of the US Constitution to keep them in check I have no doubt they would manage to virtually destroy the education system in Texas within one year of secession.
And good riddance to 'em!