I had that some horrible feeling doing a Theatre project. I just went up and my entire body froze. I couldn't think of a single word from my monologue and I was only in front of a small group of 13 that I know incredibly well. Luckily, we got 2 chances for the presentation and I did really well the next time. Then, we were required to audition for the school play (we could opt out of actually playing a part) and I was in front of like 50 people I didn't know and I nailed it without thinking at all.
tl;dr This stuff happens, keep practicing under pressure.