Short Scary Story- Church trip nightmare

The only time where I am pretty certain that I saw a ghost/something supernatural was on a church youth group trip I took in early high school. It was an all-girls trip where we stayed at a beach house in Wilmington, NC for the weekend. In the middle of the second night we were there, I woke up to one of the other girls staying in the room screaming in her sleep. I sat up, looked over, and saw a girl standing over her bed and right by where she was sleeping. At first, I thought it was just a girl who stayed in another room at first, but once I looked more closely, it wasn't. I was definitely wide awake and laid back down as I watched her walk around the bed. I noticed that there was what looked like a red and whited striped towel on the wall (which was not there when we went to sleep), and the thing that really freaked me out was that the mirror facing the two beds was pitch black. Even in darkness, you can still see somewhat of a reflection in a mirror, but not this one, it was completely black. No reflection. The girl noticed that I was looking at her — she turned around and made the nastiest, snarliest face at me. I still remember the slits of her eyes giving me that evil glare. My entire body ran cold and I began to shake, as I start screaming that there's a ghost. This doesn't wake up the girl who was shouting in her sleep, but it does wake up the other 2 girls in the room, who say go back to sleep. The ghost-girl doesn't disappear. She stands there placidly at the end of the other bed and watches us as one girl tells me to calm down. I start crying and hide under the covers until I manage to fall asleep. In the morning, I was so relieved to wake up and see the mirror back to normal and no towel hanging on the wall. Of course, I am all "ghost! ghost! there was a ghost!" in the morning, to which I receive rolled eyes and chidings of "Christians don't believe in ghosts, and you shouldn't either" (eff that, you need a better reason than that). One of the girls who I woke up starts laughing, saying she thought it was so silly of me. I run through my story - creepy girl, black mirror, red and white towel on the wall. At the mention of the towel, she stops and gives me a funny look, a look that clearly said to me that she did see something when I woke her up. I didn't say anything, but after that, if [my ghost] was brought up, she quickly changed the conversation.