Hi, I can relate totally to your worries...I have a good secure job but am SO panicked lately that I am going to lose it...sometimes the worry is justified, as I have struggled badly this year with depression, and am in a customer service position in which having a bad day is not an option.
My anxiety at work never seems to quit, especially now as we have been asked to do a "non negotiable" task that I do not believe in and which I never do at home due to the anxiety it causes - something as simple as phoning people!
Add to that in my brain fog this year I have made mistakes and was subsequently put on performance management - humiliating, as someone who had always had promotions and even owned my own business!
BUT I keep in mind, and so should you...I quit a job a few years ago as I was emotionally struggling and finding the job stressful, and was in fear of being a "disappointment" to my bosses, a failure at the job, and just plain not good enough at it - I was scared they would just let me go...
It wasn't until I handed in my notice that they told me how sad they were, that they had been HAPPY with my performance - it was only my anxiety telling me I was not good enough.
SO...TRY not to panic - even though your boss may have to give you some performance counselling, it may not be as bad as it seems...unless you are turning up drunk, stealing, abusing customers, or totally inept at your job (Which I highly doubt, as you love what you do) most employers have no grounds to ask you to leave
Take a deep breath before everything you do - try to relax, think about one thing at a time at work - you'll be fine!