I just messed up really bad

No, this isn't like some mistake in a relationship or anything. I just got off my school bus a half hour ago, I thought I sae my gramma's car so without thinking when I got off the bus I walked up to the car, opened the passenger door, and to my surprise there was some old lady sitting there. I just yelled "Oh my god I'm so sorry!!", shut the door, walkled to the driver door which the window was rolled down, and yelled to the driver "Oh my god I'm so sorry I thought you were my grandma!" Then walked away as fast as possible. The driver? Was a man. He had a beard and everything. What's worse? The kid they were picking up from the bus stop is in one of my classes. Not only that my neighbors offered me a ride right after so they probably saw and heard everything.