See the girl I like is really prude. Like she will not/does not flirt back. Once she said she was fat and ugly, basically I said she was not and all she said was "k". I just do not what to do.

She's obviously insecure. If you like this girl, your job is to reassure her she's beautiful inside and out.

I do. Oh and she knows I like her and when I told her, she started talking to me more and said we were bffls.