I allways thought of myself as a failure because after 8 years of english at school I was barely able to speak it. But now I'm about to get an degree in Computer Science and learned english by reading papers. (It's still ****** but it's enough)

Thing is: Most people are good at some things and suck at other. School just don't let you explore your talents deeply and instead focuses on thing that don't come easy to you.
Many things that you are unable to learn at school you may be able to learn with less pressure and a good mentor (if you want to. If not thats okay).
School also doesn't show you all subjects that you might be good at.

Find what interesst you. Find others that share your love. Don't think that math is more important than duno, knitting. It's just different.
I know it's hard but at least this will give you some spare time in which you will think better of yourself.

Good luck!