My boyfriends brother just got a new girlfriend and she drives me nuts!?

The reason is because she is so fake with everyone in the family. She is over the top when she talks and greets them! Every time Im mingling with someone in their family she will come over and cut right into the conversation to turn the attention on herself! And when its just me and her together she is a *****. Its almost like she tried to one up me all the time...be the nicest and most talkative! and be in competition with me and i dont know what to do. Im not as outspoken as her. What would you do if you were in my position?