so this girl

This girl was purposely ignoring me, and would rather entertain men who I clearly look better than. One time, me and my friend were having a conversation about a topic, then she joins in, of course i am willing to answer her questions. But she ignored me in front of my face, and just talked to my friend, i try to butt in because I know this topic more than everyone in the room. I feel so humiliated and feel bad to myself, one day I exploded, I am tired of this treatment, where she would constantly ignore me, and  play with my feelings. So I punched myself out of anger and spite to myself and for everyone, until I got a blackeye for myself and was suspended multiple times because of it. I dont understand how she would entertain and just be normal to other guys other than me, I am clearly nice to all these people here, especially to her, why is she like that? Why are women like that? Am I not nice enough to them? I look good, I am clealy good looking, I am atleast better than 50% of my class.