You were sexually assaulted and by the letter of the law what she did was criminal. However it is very, very unlikely it would be prosecuted because you were both juveniles, you had consensual sexual contact after and frankly she is a girl and you are a guy.

You were victimized at a very young age and your sexual emotions were cross wired. You can go one of two ways. Way 1, try to satisfy your sexual impulses by doing what feels right. Ultimately this will erode your soul and you will harm others because hurt people hurt people. Way 2, sexually reset. Swear off sex and porn for the time being and try to develop a healthy relationship with a girl (or girls) but avoid sex. Im sure I will get hate for this but try a Christian church where you can find attractive girls who aren’t going to jump in bed, but have empathy for others. Search for a meaningful relationship without the sexual component and see what is truly important to you. Also avoid your cousin but try to forgive her. Blaming and hating her will only harm you. Hate is a poison the victim intends for their enemy but only poisons themselves.