Not all change is negative. Change can often be very rewarding. A fear of change can be crippling.
Yes, it was very unexpected, and you're not very impressed at all. It wasn't what you wanted to hear, and it wasn't something that you wanted to deal with. Isn't life frustrating sometimes? Just when you thought it was safe to put your feet up, relax, and forget about some old problems, they spring up again and force you to deal with them. Stay positive. You've got plenty of experience with this sort of thing, and you'll soon be back on track. The universe isn't going to let you fall down.
If you want to overcome work-related anxiety, focus on your goals, not your performance.