I would leave her alone and wait for her to leave. I would also tell her that you'll see her at christmas holidays and talk then. She sounds manipulative and lacks consideration for his feelings. Wait until september and then do some social event thingy for the friends you missed all month. She's got some growing up to do by the sounds of it and likely will get some in her first term of collage.
People tag threads all the time. Usually its me, but not me this time. Its no biggy. No need to be paranoid. Its a compliment actually