First of all I'm sorry you are going through this. I graduated with my MSW in 2007 and luckily didn't have any issues with interns, I was the only one from my school too so it was easy to avoid drama!
As for the meeting you should just stay quiet and act like you have no idea whats wrong. Don't even mention the 'not smart' comment and get out of the meeting in one piece! No need to call the girl out on it, it will just lead to further drama!
What school do you go to? Where are you interning? I went to the Fordham/Malloy program and I interned at north shore child and family guidance center.