I was thinking about the same thing as phred said, but felt like being an asshole if I'd said that out loud. I had a long-distance relationship years ago and was sick in hospital all xmas and bed patient at home all new year holidays and couldn't travel to see him and he didn't come see me. Then when I got better he broke off over the phone & Net and it wasn't a big suprise. If she thinks you two are doing ok, start calming things and don't do anything that she might grab and say "but just a few weeks ago you were still givng good night kisses over the phone!" I don't know your reasons, but if you want to keep it civilized, give her the reasons you want to break off and try to make her see that this wasn't the best relationship for her either.
If she hadn't yet planned to marry you in few years and have kids and the whole deal and has normal level of selfrespect, she will be sad but get over it. Don't try to be friends really with her before she has found someone new. Then she might boast a bit about her new bf being good in this and that (in which you sucked), but take it like a man: now she's grown over you.
