Applications can be stressful...
Applications can be stressful BUT please remember, whatever happens, happens for the best even if it does not feel like that at the time.
You just have to trust the process, try your hardest, not doubt yourself and give it your all. After that, it is out of your hand. If you get the offer - great, if not - do not worry, it was not the best opportunity for you and your perfect job opportunity is out there waiting for you to apply :)