I dunno what to do? what should i do? help?

i have a problem with this girl, she been my frnd for quite a while, and i just noticed i got inlove with her, shes really inocent and so cool, she will talk to anyone. people said shes ugly as hell but i think shes the most beautiful angel i ever seen, i asked her out but she said she wasnt sure that she only sees me like a big bro. i have try ma best to see her like a lil sis but im in love with her, however we had a few fights before serious yelling and cursing fights but we always get back together, people think that we both are going out together. even tho is not tru, after a while a dude been trying to flirt with her and tried to touch her , but and she got scared so i got mad and beat the shyt out of the dude, but still after everything i have done for her she still dont feel what i feel, my frnds say that shes just playing around with me, but when i yelled at her and told her to get away from me cuz she was only playing with me, she begged me to comeback and even cried, and i felt really bad cuz i dont want her to suffer. now idk what to do. shud i keep on going untill she feels something for me, or shud i stay away from her before we both get hurt. HELP!!