What Fear Has Betrayal Awakened in You?

I'm a highly capable person. At twelve, I was hosting my own birthday party, routinely cooking myself dinner, doing my own laundry and checking my own homework. By 15, I was cleaning up after my alcoholic parents, discussing my mother's treatment with the psychiatric doctors at the hospital where she was held, working a job, and still maintaining an honors average at school. At 23, I was living in Europe and travelling alone to many countries.
At 25, however, in love with an emotionally undependable guy, I became the slightest bit aware that I had issues about being left. That being left, even under quite average circumstances, made me feel abandoned on a much deeper level.
The morning after my boyfriend would stay at my apartment, I would get a knot in my stomach. I would wonder if he'd stay for breakfast, would we spend the morning together, perhaps the whole day? Inevitably, he would leave: He had a squash game. He had work. He had plans with other friends. This went on for close to seven years and I developed my own coping strategies. I would leave at the same time he did to go for a run. I would mentally prep myself for his departure. I would stay at his place instead so that I was the one leaving, not him.
Therapy helped me pay attention to this deep fear of being left. Therapy helped me leave him.
Fast forward 15 years and I'm married to someone else, someone who felt far safer than this one-foot-out-the-door ex-boyfriend.
And then D-Day hit with the full impact of a meteor into my world.
And that long-dormant terror of abandonment was awakened.
Despite my tough talk, demanding that my husband get his ass home "right now if you even think you want to save this marriage!" Despite my list of non-negotiables – counselling, a 12-step group, access to his phone/computer, no contact with OW – I was shaking inside. I was nine years old again and the person upon whom my survival depended was drowning in vodka.
That's the thing with a deep emotional wound like betrayal. It awakens old fears, it underscores old messages, it says "see, I told you you weren't _______ enough." Not young enough. Not pretty enough. Not nice enough. Not sexy enough. Not a good enough daughter/wife/mother/friend.
You're too demanding. You're too bitchy. You're too busy with the kids. You're too old.
You're. Not. Loveable.
That's the biggest fear of all, isn't it? That we are not loveable. That the reason he cheated boils down to that one thing: Not loveable.
Despite evidence to the contrary, we begin obsessing on anything that supports that lie. Our college boyfriend dumped us. We've been fired from a job. A close friend stopped including us. We have crow's feet. Stretch marks. It all adds up to a mountain of evidence that WE'RE NOT LOVABLE.
And if we're not lovable, well, then what did we expect?
Most of us don't realize, at least right away, that behind the fear of telling others about our husband's affair, behind our humiliation at his cheating, behind our shame, behind our fear of drawing clear non-negotiable boundaries to keep ourselves safe is that horrible, dangerous lie. After all, if we believed ourselves lovable, we'd have absolutely no choice but to accept unequivocally that his cheating is about his failings, not ours. 
Even now, years out from D-Day and with a whole lot of therapy under my belt, I can quickly be reduced to that one fear: the terror of abandonment. The realization that I cannot control what others around me do.
Even with my Escape Plan and my understanding of boundaries. Even with my intellectual understanding that, without my husband, I will be fine. Physically, emotionally, financially fine. Even with all that, how quickly I become that nine-year-old.
These days, though, I'm able to far more quickly reach to wherever that nine-year-old sits, paralyzed, and wrap my arms around her. I'm able to assure her that she is not alone. Because I, a fully capable and sane adult, am now the one in charge.