Don’t think about them from now. Just prepare as per your schedule and don’t think of the out come
Why don't you prepare a blueprint of each subject and start by taking one easy chapter at a time. Your anxiety will ease out if you start studying because then you will have a sense of satisfaction that you are preparing.
Imagine you already failed the exam. What's the worst that would happen as a result? Something bad but you are still ok and alive? Great!
Now you know that you can survive it. Now that you know you will fail, what can you do to make the situatin better? It might actually be possible for you to do something and pass the exam. :)