I think I might know what LMo is getting at, and I'll try to pick it up from there somewhat:

SpazKatt, one time sit down, comfortably, with your eyes closed and your body relaxed and still, and simply allow the fear of abandonment to come up in you. Allow yourself to feel it. And most importantly, don't judge it. Don't fear it this time. Don't say "here it comes.. I'm so sick of it, I want it to go away." These are your feelings -- they're a part of you, and only through loving yourself and approving of yourself can you hope to heal them. Just let the feeling be present and feel how it will feel. After the feeling subsides - and it definitely will, especially because you won't be fighting with it - notice how it felt, how it felt to just let it happen, and how you feel afterwards. And notice if you feel like you have new insights into the nature of this pain. You may or you may not after the first time of doing it, but approaching this problem with a clear head will give you a lot more room to feel, heal, and understand. Just remember that this pain, and your fear of having it, are two totally separate things.