Vegeta, I understand your situation and echo many of the sentiments here. You need to move on. She is not interested in you as anything more than a friend. Also, the way you feel about her will never change, and she will not think of you as anything but her friend. This means it is toxic (to you) to stay friends with her. This happens quite often when males and females become friends and then there is unrequited love added into the mix. It certainly happened to me, and it was terrible.
Until you abandon this girl you won't be able to meet new girls that you could have a real relationship with. It took a great deal of courage for you to tell us your story here, as males do not tend to do well with talking about their emotions. However, like I said, move on and you will eventually find other girls who will be interested.
The girl you are talking about will use you for her own advantage. Best to begin limiting contact with her. Just say you are busy, etc etc. She will get the hint.
It isn't better to be friends, because you are in love with her. Are you in love with your other friends? Does hanging out with your other friends cause you emotional agony? Time to move on.