Best friend picking at MY insecurities?

Whenever I talk to her I come away feeling… bad about myself. My BFF constantly picks at the fact that I have smaller boobs than her, saying “my boobs are bigger than yours aren’t I lucky” and saying “I would look better in your dresses than you because of my boobs and curves.” she brings it up in front of other people as well. She always has to bring up my lack of boobs out of the blue. How can I tell her this hurts my feelings? I feel uncomfortable confronting her about it I don't know why.
Best friend picking at MY insecurities?
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