Wow - that's a lot to endure. Our thoughts go out to you !
Can't offer a lot of medical advice here but can try to help maybe a tiny bit with the psychological issues.
I've had a only two major illnesses/injuries in my lifetime and one thing I noticed is that it's a bit of a battle to overcome phantom symptoms for a long while after the injury is technically healed.
I can only say - and with full realization that action is much harder than theory - that we DO have tremendous control over our brain function. But it takes a lot of work and you absolutely MUST believe in that capability 1000 % ! A common example most people have seen is fire walking. There's lots more. But you have to BELIEVE that it's YOUR brain and that YOU are in control - not "it". Which is largely scientifically proven so it's not hard to believe. But it's not what we were taught initially in science class.
I had my neck broken in 3 places this spring and still suffer some discomfort - a part of which I know is phantom. I also have nerve damage and have just been patient waiting to see if it will regenerate. Med science claims that nerves regenerate much slower than other tissue and to not be concerned for at least a year. Before much longer my patience will be exhausted and then I'm going to pursue a more complete confrontation with my brain to retrain it to accept the new condition as healed & normal.
In your case it seems the most worthwhile effort would be to address the underlying phobia you spoke of as your injury/surgery unfortunately ties into the same fear. Maybe someone with the proper background could make some suggestions on how to overcome that particular phobia.
Maybe try intentionally restricting your breath (by holding it). The more your brain realizes that temporary lack of oxygen is not the signal to go into 5 alarm mode immediately the better it will respond. This is pretty common in people with panic disorder as one of the primary symptoms of a panic attack is hyperventilation reducing oxygen. It's a chicken/egg problem and one of the first things you are usually trained to do to fight panic attacks is deep breathing exercises. I'm sure someone has already gone that route with you.
Good luck - stay positive and take control !