I'm that kind of person who laughs uncontrollably one hour to distract myself from negative thoughts, tricking my mind that I'm happy, but cry the next because I know I was just lying to myself.

I finally did my presentation yesterday, which sucked balls. And the feedback was terrible. I was an hour late, I couldn't answer all the questions even simpler ones, and he was so frustrated that he didn't even want to really talk to me or look at my face. I tried to forget this particular scene to avoid downgrading myself but I couldn't. The memory keeps replaying itself in my mind. And each time, I hate myself more and more. I think I'm gonna fail all subjects this semester. I know I can't afford it. I'm fighting the urge to give up. I'm fighting.

I don't see a way out. How do you be positive?