Finals week is probably the most stressful week of the semester. Whether you need a 100% just to pass a class, waited too long to start a project, or honestly, just don't feel prepared no matter how hard you studied, it's all normal. Though I do feel like a lot of stress of finals week can be spared by just preparing earlier, that isn't always do-able.
It's OK to be unprepared, but you have to accept that it is your fault. It is ok to fail a class, as long as you are willing to take responsibility for the failure, learn from your mistakes, and not repeat them.
We, the student body as a whole, feel so much pressure on ourselves to be the best, most well rounded, straight-A students, which can ruin the experience. This includes me.
That definition of who I have to be in my head has been the hardest part about succeeding in college. No matter how well I actually did, I always felt like I could be doing better; doing more. I'm here to reassure you that with everything you're doing, you're doing fine. There is no perfect student, who you are as a student should be enough for you, as long as you are working as hard as you can and putting your best foot forward.
Finals, no matter the outcome, don't define you. yes, your GPA matters for scholarships, entry into closed majors, etc. I guarantee your future employer will not turn you away because you got a B in Calc 3. It is over, there is nothing you can do about it now, just know that there is a plan for everyone, and no mistake you made this semester is unfixable. Take a breather, you're doing fine.