My problem: social anxiety

Hey! I'm back from school so I decided to share something with you. I don't even know how I did this because often I'm scared, but this is the only way.

I have social anxiety which is really hard for me especially when I'm presenting in front of the people. Today I had to present in front of 20+ people and I was feeling uncomfortable and I'm still shaking a little bit and worrying what they think about me, I'm so scared right now and I don't even know how I function.
Here's how it happened:
It was another bad day for me in the school, I got 1 (F) and then Geography class came. It became worse that it couldn't get any worse. Teacher said that she's gonna pick few people for presentations and I was praying to God not to be me, I was really nervous and then she opened me and said my name, it was like hell. So I made it and today I presented, I was letting other people to go before me because I was scared. My time came and I sat on the chair in front of my classmates and my teacher, I didn't feel comfortable. I was saying everything so fast that I don't even know if they understood anything, I was slightly shaking too, but they didn't notice it, I hope. The problem was even bigger when I couldn't find arrow keys on laptop and they started yelling "Press the arrow keys", but I was in kind of panic and then I pressed random button. After I was done with presenting I just didn't know what to do, so I went to my seat and teacher asked other what they think about it, another bad moment, wow 3 in row. I just couldn't wait till I get home and share this with someone, somehow.
Nobody, expect my mom, knows that I have social anxiety, it's giving me a big problems in my life, like HUGE. Why me?