welcome lucky to pc. so glad u're doing well after so many issues from the accident.
i was in 2 bad accidents within 6 months of each other-not my fault. one a head on collision. i'm still concerned about that but have brought that fear under control. after the second one- while on the interstate someone fell asleep at the wheel right next to me. i honked as a warning-they were coming into my lane. didn't know the lady was asleep. she overcorrected when i woke her up with the honk. ended up hitting me broadside at a high speed. i still have anxiety if someone drives close to me 6 yrs. later.
it sounds like to me u're having a panic attack-can't breathe. not able to calm down, etc. pulling off the road was the best thing you did. when i had them one helpful thing i did was to mentally tell myself i wasn't going to die from the symptoms of the panic attack. hard to do but i'd calm down faster.
maybe do some driving in places u're familiar with and little traffic that will give you renewed confidence and slowly you will feel more comfortable driving.