Hiya,
Its great to heat that you managed to get out and have some good quality time with your friend. Even though you couldnt tell her everything (And I understand why) it must have been nice just to get out of the house. I think the fear of failing is something a lot of students (myself included) ahave to fight on occasions, and it is harder when you are trying to make a parent/parents proud. Please hang in there though. Im sure if you were not capable of passing the course, the school would not let you do it. If the school believe in you then I see no reason why I shouldnt believe in you as well. If you can say you have done your best at the end, then passing/failing should be irrelevant to your parents.
Darren