There's no real reliable narrator to this story, so it's difficult to tell how much truth there is to the MC's statements. Knowing about the other stories the author has written, she probably did sleep with the others. An extreme response to being hurt for sure, and 100% toxic behavior, if she truly did. That's life though. Although her statement about men and women hurt each other can come off as her feeling nonchalant about the whole experience, I do think it is a sign that she grew from the experience. I'm less inclined to believe she's still a toxic person because of it. People are messy. We're incredibly stupid when we're young, and many of us never realize how dumb we were. It leads to messy relationships, and to people who are hurt hurting other people back in return. I like the premise of this story, and because of that I'm dissatisfied with it being a one-shot. Wouldn't have to be a full series, but a one-volume short story made out of this could do a lot to flesh out the girl.
As a side note, it kind of seems to me like the girl probably fell in love with him before joining the circle, and changed herself to be what she thought would appeal to him. Not in she's a "fake gamer/nerd" type of way, but rather acting the way she did (like an anime character almost), and dressing up for him and asking him to take photos of her was something she wouldn't have done for a guy she didn't feel strongly about. I think having that in mind at least makes it more understandable for why she would have such a strong negative reaction to his negative reaction of her body. Do all that because you genuinely love a guy only to see him be visibly frightened and grossed out by your pussy must be mind-shattering in it's own right. Also could be true that his friends were right about her faking being into their hobbies just so she could hang out with him, which makes his reaction kind of worse. She did all that for you buddy, and you blew it.