Dub, exposure therapy is slowly training our brain that we arent really going to die when think about flying IN a plane. Getting ON a plane, well, you probably would die on the take off, so exposure therapy would just be a waste of time.
In exposure therapy, they take people to the airport and sit in the parking lot and listen to their favorite music. When they can relax in the parking lot, then they take them to sit in front of the terminal and listen to the music until they can relax while being just that little bit closer to even seeing the plane that someday they want to get INTO. Anyway you see the progression of training the brain that nothing scary here, lets just take small steps as the brain learns it doenst have to protect us from basic survival fears.
So, watch videos, tracks, while touching the joystick, holding the joystick, pay attention to the nasuea feeling, and take time to work through the first warning feelings. Can you wear the VR gear even if just on top of your head while doing something fun? or music?. Dis-associate the fear of nausea with changing the physical motions you go through, until the brain says, shit, this aint what Im supposed to keep the meat sack away from, and maybe over time this "see a snake, faint" feeling will subside.