The likelihood is incredibly slim.
The science stuff is basically all false - a quick look at NASA's webpages will tell you that. It's pseudoscience basically - false.
The Mayan stuff - had you honestly ever heard of the Mayans before hearing about 2012? Other than those of us who specifically go out of our way to study such peoples very few will have come across the tribe, or you might know the name but not much else (just like the Aztec, the Incas etc). It seems they were pretty good at predicting the lunar cycles - which is probably a question of good mathematical understanding and tracking what they see the moon doing.
I have never heard of them making any other credible predictions - which does make you wonder why so many people are now trusting in them.
Not only that - but the predictions (all 2 of them, and they were pretty much ilegible and had to be translated) are somewhat specific to their own beliefs and Gods.
On top of that - what can be read (that they "wrote") refers to dates other than 2012 and extends far beyond into the future.
The Mayans that still exist aren't worried either and are saying the end of a cycle is seen as a cause of great celebration (just like we had when we celebrated the millenium)
The believers - the publicised ones - appear to be either a) very mentally ill, b) believers in all manner of oddities and pseudoscience or c) trying to cash in - one of the bigger websites is trying to sell t shirts and survival guides for goodness sake.
www.2012hoax.org/ - is the best place to go, run by credible scientists.
I seriously wouldn't worry if you can help it - try to focus on Christmas instead, plan something nice for the 21st.
I have anxiety too and have been worrying like crazy about this, have done a lot of research into it to try and calm myself down lol.