In kind of a tough situation, I don't want to be a jerk?

So my brother's girlfriend is living with us this summer until she goes to college in the fall, because her family isn't very supportive and they don't feed her. Its been a little over a month but I'm getting kind of sick of her. We went on a trip and she sang to my brother in this baby talk the entire 7 hours back home! And she makes fun of me because I'm kind of a shopaholic. We went to the mall the other day and I bought some makeup and she was like "that's 1/4 of $100" and she makes fun of me for buying so much nail polish, but then she goes and borrows it. I don't care if she borrows it, but not if she makes fun of me for it. She makes fun of me because I shop so much, but I just gave her a bunch of clothes like more than an entire trash bag full. And she told my brother I manipulate my mom in to doing whatever I want. My mom does usually let me do what I want, but I don't manipulate her. I just really don't like her coming in and judging me. I understand that I am very blessed and she well wasn't, but I am just kind of sick of it. I just don't know what to do.