You seem to be very aware of your issues and present them in a logical way...are you able to "reason" yourself out of your feelings of insecurity when they arise? I have similar feelings from time to time and also realize, in my logical moments, that my feelings really aren't based on reality or even anything tangible (such as evidence of a cheating partner)...so, when panic sets in, I really can only talk myself down by presenting myself with the "facts." And, at the end of the analysis, the facts do not support my initial (albeit delusional) conclusion....sometimes I feel as if I'm two people...they panicky insecure one and then the more logical assured one...I can get myself from one to the other in a manner of minutes...so, I try to exercise more discipline with myself (w/r/t negative fantasies that usually involve the worst case scenario) and tell myself that any dwelling in the negative place just makes no sense...I usually try to let my logical side beat my irrational side unless I'm feeling self-indulgent....if any of this makes sense.

Imagining the worst case scenario as a means of preparing for the possibility is a horrible way to go...I've done this since I was young and cannot seem to completely get rid of this very dangerous habit. My father cheated on my mother and she was publicly embarresses when it all came out....I promised myself to never be that unaware...only problem is that I'm hyper-aware to the point of walking myself through the situation should it ever occur. Very damaging to my relationships in that I can sometimes get so upset (over something that has never happened), that it spills over into "reality"....kind of like waking up from a bad dream and feeling as if it really might have happened. Of course, I know the difference and am aware of my "worst case scenario fantasies," but it affects my mood, regardless.