Thanks for telling us. I am glad you are starting therapy, is it CBT? As you haven't had therapy before, you should notice a reduction in your anxiety when you get an understanding of it. You will learn to manage your panic and live with it, and eventually it will go completely.
The thing you did that made you feel guilty needs sorting out...Often anxiety is caused by a problem hanging over you and the weight of it over a long time gets worse and worse. Can you try to come to some compromise over your problem so you can shed the wieght of it?
It helps most not to fight the anxiety, but to accept the horrible feelings for now as they will pass. It is not a permanent thing and you can't feel too bad for long. Don't limit what you do, but make sure you are eating properly even if you don't feel like it, and resting up when you can. Stay occupied and don't dwell on it. And keep your faith