Hey, way to go in terms of making the decision to stop the codeine! That's a huge step!
Right now, things are going to feel kinda extra awful. It's part of withdrawing. It will get better.
Your pysch sounds like a good doc.
I've taken antipsychotics myself. One of them did wonders for my anxiety. Yeah, I was hesitant to, but
@joeylittle is right - antipsychotics are used for a number of things. They basically help slow down nerves that are firing too fast, which is what could be playing a role in your hyperarousal symptoms.
It may be wise to not drive while you figure all this out. I drove one when I had a ton of symptoms and crashed my car. It's something I'm still paying for two years later. :( Disabiloty sucks, but it might give you te resources to really focus on your recovery and building a different and better future. It's all hard steps either way. For now, try to just focus on today and getting through.
Has your treatment team talked to you about things like deep breathing? It sounds silly, but training ourselves to take slow deep breaths, in through the nose and out through the mouth - this actually sends a signal to the body to calm down. It's has a stronger effect over time. It's not a complete solution, but it might help a little with the symptoms you are experiencing now.
Keep up the good work!