What is this? The emo corner? Grow up. The only mistake any of you have made is having regrets. Find pride in all that you've ever done, because you've already done it, and that's it.
I've done stupid shit in my life, but I had fun doing it while I was doing it, and that short moment of joy is all we can hope for when most of us can't see a week ahead in our own lives to plan for success in the long term.
My grades are all Cs in High School now and have been since I left the 5th grade, and if it fucks me over in my future, you have my word I won't blink. I had fun, and that's all that matters in life. Make the most of the time you have.
Sorry if I'm coming off bitter, but sulking in your own shit doesn't go very far to improving self-worth. Excuse the old adage, but it's truer than the blue of sky, "Don't cry over spilled milk."