The only degrees that will always require you to keep up your grades are Law and Medicine, because they are so competitive. Whenever you take a test, remember that it's pretty much insignificant in the end if you don't score the highest. The important thing about a college application is not the transcript, but the resume. What can you bring to the institution that sets you apart from everyone else. Sure a high grade looks impressive, but a resume that shows your dedication for whatever it is you love to do is so much more.

You say you are worried a bad grade will end your future, well that is defiantly not the case at all. It was also simply a practice test, so getting some questions wrong is actually kinda a blessing in disguise. Take a look at the test, see what it is you got wrong, and learn from those mistakes. Your friend did better then you, but don't worry about that. Talk to either your parents or teachers and see what you can do to study without sacrificing sleep, or if college is what you even need for your future. A lot of people go to college, then decide they don't need it and leave.

The most important thing is to remember you are not yet at an edge. The sooner you stop thinking you already failed, the easier it will be to start making some actions to start moving towards your personal goal. if you have any questions academically, the Study Hall forum is your friend, just make a thread with what confuses you, and members will help explain to you what it is you are unsure of. Have some confidence in yourself, you can do it!