Hello there, Mrs Pink,
"....does anyone else think they might be afraid of being slim, and therefore sabotage their own dieting attempts?...."
It's a really good question. I, like yourself and tishtosh, don't ever remember being slim. I had never bought a size 14, 12 or 10 in anything before completing LL. I could not imagine what I would look like being slim. I had dieting for thirty years trying to get slim, and just got fatter instead.
Being slim is 'the unknown' and therefore out of our comfort zone. Being slim means lots of positive things but it also means saying 'no' to yourself and being responsible for what you do to yourself. It can mean lots of attention from others (being sexually attractive) - that can be hard to deal with, and threatening. It can mean that you can't use your excess weight as an excuse any more i.e.
"they don't like me because of my size" - if you are slim and they don't like you, you must look somewhere else for the reason.
"I didn't get the job because of my size" - ditto.
Some time ago I was reading a thread from someone who had shed a lot of weight and could now go paragliding, something they had wanted to do on holiday for a long time, but the excess weight had prevented it. Interestingly, they decided that they didn't want to do it any more once they got to goal.
So, we use the excess weight to our advantage when it suits us. We can use it to excuse us from any situation, or a reason for failure. It is a comfort and a refuge.
"....It was like I was saying goodbye to an old friend, I think I hid behind my weight for so long, I probably felt I was going to miss being fat....."
Cherry Plum, that makes a lot of sense...