I have had similar struggles with the depression, the loss followed by the gain, the loss and gain loss and gain cycle. It does suck, and it does sap your energy and makes you feel worse about it rather than pumped and excited.
Do you have any of your old clothes that you wore when you were 320? I find it that when I am feeling like I am a failure, I put those size 18 jeans on and see how baggy they are on me and instantly I see how far I have come. Think about the positive changes you have made rather than the mistakes.
Have you gained more since last year or maintained? I am maintaining right now but want to be losing, but with the depression and school and wedding planning I am very satisfied with maintaining and just keeping afloat for now.
Did you know that exercise is one of the best things you can do for depression? Seriously, I do not look at exercise as a way to lose weight or get fit, I look at it as the thing I need to do to keep the depression from taking over my life again. I was unable to work this summer and have been having a hard time in school cuz of the depression and the exercise really really helps. I know the energy isn't there, and the motivation to get there is difficult. But if you can just tell yourself that this is what you need to do to make yourself happy and you can just get outside for a 20 min walk, or do any kind of activity you like on a regular basis, you will notice a difference with the stress and depression. I have also been using a SAD lamp for a few weeks now (for seasonal affective disorder, also effective for depression) and can notice a difference in my energy levels and mood. I am lucky to be able to borrow one, they are kind of expensive but really worth it as a natural way to treat depression. Google it, there is tons of info out there about light therapy.
I am not sure if you are diagnosed with depression and taking medications or anything, but if you haven't spoken to your doctor about this, it is something that you should probably do. It sounds like the depression is what is getting in your way, and you are very hard on yourself. Depression makes the way you think about things different and more likely negative which only perpetuates the bad feelings etc.
Comfort eating and eating junk food is very effective at making you feel ok in the short term, but look at how it is affecting you now. Binging is an ineffective coping skill to dealing with feelings and stress and it is something that makes you feel like more of a failure with the weight loss because the 2 cannot go together. You are not a failure at all, you are simply struggling to find a more effective way to cope with depression, stress, emotions and life.
Sorry for the long post, in my final year of school for nursing and just completed a placement in a mental health facility. So between working with others who suffer from depression as well as being someone who has depression I am very passionate about this issue. I hope you will keep us updated on how you are doing, don't disappear again! Its those times when you disappear and don't reach out for support when you probably need the support the most.