Red
Here is a quick fix that may get you through this. I presume you have had other outings that you survived. Write them down in a column, the more the better but even just one will do.
Beside each write what happened and though it was bad you are still here and it didn't kill you. Then write the good things you remembered about each outing. Find more good things than bad. Now comes the interesting part. Since a good part of the problem is thought. Negative thought to be sure. Challenge each one of those negative thoughts.
"I'm not going to pass out, (or puke) other people don't." "My partner is here and he is not going to pass out, so I won't either" " I didn't last time so why will I now, I'm just being silly." Right about here you probably think ,"What does he know". Been there done that. I KNOW this works. Ask others.
Any thought will do and if they turn into a mantra all the better. Your partner is your safe spot. When the pressure starts to build use him for a distraction. Count his buttons, check the lint in his pockets, (ears, what ever) The busier you are the less room for negative thought to enter your mind. Any calm distraction you can concentrate on will do.
This is important. Don't choke up. Breath slowly but normally. Look up box breathing and learn it.
And the really important one is this "I can do this for my partner, I can crash and cry when I get home."
Believe me there is a reason behind why these work.
Oh and the biggy. My heart is running too fast. It is supposed to!! You are doing something exciting it will slow down if you let it. Your partner can support you by keeping you occupied But not by asking you any thing you will have to think on too hard. And above all DO NOT let him ask if you want to go. This is suggestive and then you will have to. As a last resort close your eyes and say ,"I am Ok, I can do this."
Have to go I have an appointment.
Good luck.
Davit.