How to tell a girl you cant be just friends?

I have spent the last 6 months with the coolest girl I have every known. We do everything together. It wasnt til I found myself becoming jelous of my guy friends who would flirt with her that I realized I have completly fallen for her. I distanced myself from her til she asked me why we were no longer hanging....I told her because I like her more than a friend. She brushed it off and still wants to be friends but I cant do it....I love everything about her. Friends is painfull. She doesnt understand....what can I say? She text me everyday....