Hey, it's going to be okay. It's always turned out to be okay in the end so far, hasn't it? Please try the breathing exercise to help with the physical symptoms.
I have a theory why it happens like that. Just a theory, but maybe it'll help. Sometimes we can do something that seems huge and then we realize it wasn't that bad. So then we get upset that it wasn't that hard to do and get angry at ourselves for not doing it sooner, or better, or whatever. Seems like a perfectionism thing. Please take progress over perfection. Perfection is an illusion when it comes to what people can do. But we can make progress.
Sometimes we're surprised we didn't fail! I think that comes from early life influences turning into negative self-talk. For example, math was my worst subject in public school because I couldn't memorize multiplication tables. So I got told I was no good at math. For awhile I tried to do better. I did. I came home with a test once with a near perfect score. I only missed one question. The response from my dad? "Why did you get that one wrong?" Seriously, WTF? Who says that to a kid? From that day on, I did everything I could to avoid math. Now that I have to do it, it's getting easier to learn and my confidence is getting better. I still don't know my multiplication tables to13 like some 4th graders do, but I'm making progress. I beat myself up a bit for not learning it earlier, but I also gave myself break and realized I'm doing it now! Now! Better than never. That's going to have to be good enough for me.
Maybe that's how it is for you. I don't know. But you did it. You made it through shopping and sounds like you had FUN doing it. You are allowed to have fun overcoming a fear. You are allowed to still have that fear a bit and to work on it some more. You know how I know you're allowed? Because you are the one that gives you permission.
I'm tired and rambling, yet I want you to know I'm proud of your accomplishment and I'm a complete stranger! You can rest in some pride in your accomplishment too!