Bridesmaid Problems

I have having problems with one of my bridesmaids. I have two other bridesmaids and one maid of honor so four attendents total. I got engaged two months ago and am getting married Jan. 26th. One of my bridesmaids still hasn`t ordered her dress offline as the other 3 did 2 months ago. My bridal shower was this past saturday. This bridesmaid showed up in tennis shoes and a tshirt. I wore jeans but not tennis shoes and a tshirt. I felt so disrespected. She didn`t helped set up or clean up. She complained about having to serve guests drinks, so I the bride did it mostly. She gossiped every second she got, to me. She complained about doing anything and gossiped about everything. She made my bridal shower miserable. By the way she is married. I expected more from her being that I am 20 years old and she is 31 years old. I want her out of my wedding. I am losing sleeping. She is not the type of person you can talk too. She is kinda psycho; she is never wrong about anything. Also, she didn`t even bring a gift to my shower not even a card. Plus, I might add ,myself and two of her other bridesmaid paid for her whole shower while I was still in high school a few years back, I was only a senior in high school. I just need her out please help!! I should have gave it more thought before asking her to be a bridesmaid. She is self-centered. Please help!! How can I get her out?