I had to break up with my previous boyfriend from home a few months into uni. Unfortunately, i don't believe in a good break up and mine was even worse. I went home for the weekend especially to do it and he didn't bother to come over so i had to do it by letter, then he hadn't told me he was away that week so he didn't get the letter til the end of the week which just happened to be on his birthday, mine was two days later. He was obviously devestated and to cap it all almost a year on he keeps telling me he still loves me.
To the OP, basically you can't keep leading her on like this and you let her hold you back from all these suposedly great oppurtunities, its not fair on you or her. Be kind, do it gently and face to face, yes she will cry, you might do too, be strong, don't let her tears keep you from believe that what you are doing is right and for the best.