It sounds funny but I think your fear of losing her is what has been driving her her away. You're not alone...I've done the same thing. The first thing is don't worry about this other guy, because if you do you're going to make yourself sick over something you can't control. The second is to take a step back give her some space. If you just simply cannot leave her completely alone settle for a simple Email...assuming its ok with her. While you're taking a step back try to see things from her persepective.
And as for her saying that she loves you she just doesn't want to be with you...I can think of a couple of things first of all being the hard truth that she does love you she's just not in love with you OR there's that She like doesn't want to have to worry about everything she does that she loves you she just can't handle the jealousy thing then again it could simply be that being away from each other and fighting so much is just wearing her down....
Just give it some time...either way....things will work out how they're suppose to