I found your post purely by googling "depression after weight loss". I'm going through exactly the same thing. I lost 115 pounds, having been overweight my entirely life. I've suffered from both depression and anxiety in my earlier life and it's recently come back post-weightloss.
You assume you'll feel happy, confident and positive once the weight has gone but it's the reverse for me. I've found myself behaving in ways I'd never behaved before. People seem to like me finally, but it isn't the real me. Sure, guys have started noticing me for the first time but I don't trust them and I am certainly have trouble letting my guard down to get close to any of them.
Most of all I feel completely unsettled, unsure of myself, and absolutely petrified of committing to anything for fear it's all one big "gotcha" joke. And with the emotional highs and lows, I am convinced people think I'm scatterbrained and useless. And the strangest part is that I still identify myself as a 'big girl'. I was happier when I thought I had no hope. Now that I can see what has been denied me my entire life, I am so afraid and overwhelmed by the future that it's crippling me professionally and personally.
Please feel free to email me or read about some of the ups and downs in my blog. link removed