just so upset

So my bf went out with his friends. This one girl wore a dress identical to mine. All my bf keeps saying is how nice it is ect. I sent a picture of me in mine. I said babe hers doesn't fit her ass is falling out and you can see how tight it fit her. I could look the same if I bought an xs when I'm a medium. Like wtf why does it matter to tell me what she is wearing ect. It upsets me so much