The day after sticking to my decision and the day after the day after announcing it, a very strange feeling came over me, and one I absolutely did not see coming (at least not in the context of leaving my job). It wasn't regret or guilt or relief. It was sadness, and it was intense. Being so unexpected, I had no way of coping with it and had to let it take over for awhile. It was the last thing I expected to feel, and it brought with it a compassion for the people I'm leaving behind at my job. All these years I knew I was valuable, but I would not have guessed that my value transferred so extensively to a personal level. It took me by surprise, and my shock manifested as a deep, deep sadness over the mutual (if temporary) emptiness my boss and I will both feel. To be cared for, even if it's not always healthy or mutually beneficial, is a powerful and special thing.
The important things are to know when to move on and to be able to separate emotions from actions. Part of my sadness, if I am to analyze myself, comes from having made a decision I believed to be a practical and unemotional one that turned out to have an unexpected consequence: a genuine emotional reaction from my boss, which in turned sparked my own. I was prepared for a fight, but I wasn't prepared for a hug.
In any case, I have to deal with, learn from, and be thankful for these strange feelings as they pop up. I have to realize that a certain amount of discomfort is going to come with a new beginning. I have to give myself a chance, or I'll never know either how good I've had it or how much I've been missing.