First, thanks for sharing your story as I'm sure that was hard when you still have such an intense reaction to it. Second, I'm not a doctor but I went through a period of my life where I did LOADS of drugs and know quite a bit about them. So, with that said, my two cents...

From how you describe the high it sounds like it was laced with some sort of speed (hard to say what kind). For someone with an anxiety disorder this is a terrible idea as it's going to feel like a health problem (heart attack or an asthma attack) and while high it's a slam dunk that that's going to cause a panic attack which in turn will feed into itself.

I think after that you were so traumatized by it that you now get the same panic attack when you think about it. If it were me the way I'd try to fix that is to get some evidence that I'm ok. A simple doctor visit could do it. Just, ya know, go in and get checked out. Tell them what happened if you want or just let them look you over generally and then you can reassure yourself with your newly acquired clean bill of health.

The only thing I can say that might make you feel better is that it's incredibly unlikely that the drug did anything permanent to you. And the things it could do aren't the things you describe. Also, if I'm right and it's speed there's no chance you still have any appreciable amounts in your system. Same with THC from pot, you've pretty much processed it. Now, don't get me wrong, you probably wouldn't pass a drug test right now but there's nothing in your body that you would actually re-experience, if you get my drift.

Again, I'm not a doctor but I think you'll be ok. And stop doing drugs, they don't agree with you.

Cyran0