Is Texas Secession even Possible? Can other States Secede?

Growing up in Texas, I have always been familiar with the idea of Secession.  In school I was taught that Texas had the right to Secede as it was once it's own independent nation (republic).  I was also taught that Texas was the ONLY State that had that right!
Over the last several years, talks of Secession have come about numerous times for a variety of different reasons.  There are those that believe that Texas was never properly admitted into the Union in the first place, and others that think Texas still belongs to Mexico, and others still that just simply don't like the Federal Government.  Then there seem to be a large majority of folks who believe that Secession would be suicide, that the Federal Government wont 'allow' it, that the talk of secession is 'Treason', or that its simply just not 'legal'.
No matter which category you fall into, there seems to be a LOT of misinformation, and a WHOLE lot of questions, out there regarding Secession.
Without getting into the claims that Texas was never properly 'Ratified' (or whatever other terminology you may choose) or the claim that Texas 'still belongs' to Mexico; the fact is that Texas IS a MEMBER of the United States of America today.  With that in mind, lets look at the makeup of the good ol' US of A.  Each State is an individual 'entity' in 'Union' with the other 49.  The United States of America is exactly that, 50 individual and independent States, united through a common interest, goal, and purpose.
The US Constitution was designed lay out the relationship between the States and to limit the power of the Federal Government.  The 10th Amendment states that any powers not expressly granted to the Federal Government by the Constitution, nor prohibited to the States, are reserved to the States or the People.
In the interest of staying on track with our discussion of Secession; the question at this point begs to be asked; Is Secession, or withdraw from the Union, prohibited to the States?  Or, conversely, is the ability to refuse withdraw from the Union granted to the Fed?  In both cases the answer is a resounding NO!
Article I, Section 8  (Wiki) is a list of the 18 powers expressly granted to the Federal Government in the Constitution.  Not a single one of them even remotely implies any power over or possession of any or all of the 'several states'.
Article 1, Section 10 of the US Constitution lays out the 6 things that are prohibited to the States.
During the Civil War, the Federal Government stated that the 'Confederacy' could not be a legal entity due to the provision in A1, S10 that States could not enter into Alliance or Confederation, or make a Compact (agreement) with another state.  Do you remember math class?  In math there is an 'order of operations' (PEMDAS).  If you do things out of order you will not get the correct answer.  The same applies here.  While no State that is a member of the Union may enter into a Confederation, no where is said State Prohibited from leaving the Union!  Did you catch that?  The question becomes, did the State leave the Union prior to joining the Confederacy?  Once a State leaves the Union, it is no longer governed by the Union constitution and thus no longer prohibited from joining into any contract or confederation that it so chooses!  So, Assuming that a State first removes itself from the Union (thus becoming completely independent of Union rule), then joins a separate Union (Confederacy), then there is no question of legality of the new Confederacy!  I don't know exactly how it all happened during the Civil War, and this isn't a discussion of History, this is an analysis of current legality; so, moving on...
Given the fact that we have now established that the Federal Government does not have the power to prevent or refuse an individual States decision to remove itself from the Union, and the States individually are not prohibited from leaving; it would appear that any and all States, individually, have the Right to Secede!  What is prohibited is States (collectively) forming an alliance or confederation before Secession.
Now that we have looked at this from the standpoint of the US Constitution, what else could be a factor in this legality?  Well, each State also has it's own Constitution that governs it's people and lays out it's relationship with the other States and the Federal Government.
I will apologize to all Non-Texans now, as I know very little about any individual State's Constitution other than Texas', and quite frankly, being a Texan, I simply don't feel like looking them all up and analyzing them!  However, if you happen to have an analysis of your State's Constitution that would apply here, please feel free to post it in the comments!
Disclaimers over, lets move on to Texas' Constitution and see if it prohibits or even limits our ability to Secede.  It has often been said that the 'Right to Secede' is protected by the Texas Constitution; however, no where in the text of the Texas Constitution is 'Secession' expressly mentioned, nor is it denied!
Article I, Section 1 states that "Texas is a free and independent State, subject only to the Constitution of the United States".  We have already established that the US Constitution does not prohibit us from Secession, and now we have established that we are only subject to the US Constitution itself, and not to the Federal Government, or its various whims of fancy.  So, there is no conflict here.
Section 2 states: " All political power is inherent in the people and all free governments are founded on their authority, and instituted for their benefit. The faith of the people of Texas stands pledged to the preservation of a republican form of government, and, subject to this limitation only, they have at all times the inalienable right to alter, reform or abolish their government in such manner as they may think expedient."  Well, I'll be...  If We the People have the right to 'alter, reform or abolish...' then it would seem to me that We the People can certainly choose to Secede!  I have found no other writing in Texas' Constitution that would prohibit us from removing ourselves from the Union.

Of course, whether technically legal or not, none of this would necessarily prevent the Federal Government from declaring War upon the newly independent State or States as we have seen in History through the Civil War!
There are many practical concerns to be considered before simply saying 'Goodbye' to the Nation that we have been a part of for so long, and becoming once again a Free and Independent Nation or Republic would be a very long and difficult road for sure, which is a discussion for another time.  But the Fact remains, that, YES, Texas CAN Secede if its people so choose, and likely so can any other Independent State of the Union depending upon it's own Constitution. 
Either we are Free or We are Slaves!  I choose to be Free!