Whatever happens, I know you'll get through it.

I am so sorry for the response you got from your mother. Here for you.

I think you have a heck of a lot more guts than I do for even attempting to take your driving test. I won't even take lessons!

I know it must seem like an absolute disaster, especially at the time. But let's reframe the situation a bit and turn those downsides into some positives - Now you know what could happen next time. You now have the ability to take precautions and make whomever is administering your test, aware of your situation. Possibly even look into a more specialised instructor administering the test so they would know how to help handle the situation a lot more. Alternatively, you could also look into finding out who may be administering your test in the future and get to know them a little more beforehand. Not necessarily to make friends with them, but to at least build up some sort of rapport so having a new person in the car with you won't feel so alien.