We all have to deal with a 'Carla' at some point in our life. Rather there's always one at every time. Just deal with it. i'd say, you need to show this Carla that her presence/absence/liking/hatred doesnt matter to you AT ALL, that you give **** to what she thinks or does! Instead of taking out your frustration on other colleagues and co-workers, give this Carla a little hard time IF you must. But the best would be to just let it go. You dont need to befriend this young lady, trust me on this.