Why Did I Do That?

So there's this thing with my sister and me. We're both pretty competitive, but it got out of hand one summer when she won a game at camp that was supposed to decide who gets the last slice of pizza back home. I was so mad because I thought I had won and then she just took off running around telling everyone before we even left camp. Ever since then, every little thing seems to escalate between us. Anyway, last week during family dinner, my parents were asking me about a project at school that I was stressing over. I'm not exaggerating when I say it felt like everyone was staring and waiting for something dramatic from me. Suddenly, before I knew what was happening, out of the blue (or maybe just because I needed to shift attention elsewhere), I blurted out, 'Oh my god, I think I failed a test last week!' This got everyone's attention, including my sister who looked like she was about to lose it, and me, well, I had this sinking feeling that I might have crossed a line. I ended up making it worse because when my dad asked for details, all I could do was stammer and say, 'But... but I didn't really fail. I just thought maybe...' The whole night felt weird after that; everyone kept looking between me and my sister like there was some secret code we were sharing. I mean, honestly, why did I even bring up something so silly? It's not like it actually happened. It feels like I'm stuck in a cycle of doing these things without thinking. Did I just want attention or was it more to try and make my sister look bad because she always seems so perfect in their eyes? So now, every time someone asks how school is going, I feel sick to my stomach, wondering if anyone remembers that day. I've never felt like such an idiot before. It's just a real reminder of what can happen when you let your emotions run wild and say things without thinking first.