I'm not in any way taking sides or anything, and do definitely believe that everything Metaltastic has said is completely true, depression is an illness. I guess this is kinda off the topic of how you're feeling, but more to back up what dan said, because over the past year I've realised how much difference your diet does make.
I used to have really bad phases of being quite a horrible person, went through sabbotaging relationships with chicks and quit playing my guitar for at least 8 months in 2006. About 4 months into 2007, and after (What I believe, anyway) my poor diet got me to the point of having renal troubles, I started working out, and more specifically it seems, drinking around 3 litres of water a day instead of sugary soft drinks. 4 months of that (I guess it took that long to purge the toxins in my system) and I felt like a new man. The first time I really noticed how much of a massive change had taken place was Festival season. I used to feel like SHIT at festivals, but this year I was a machine, I couldn;t be stopped. I was moshing for 8 hours a day, and with each new day just wanted more!
I kept that up for a year, and recently swayed back on to junk food and soft drinks, and I just fucked yet another relationship up. It's taken about a month for me to fuck myself up again and undo everything. I'm sorting myself out now. Hopefully it won't be another 4 month cycle.
The shit you fuel your body with is the most important thing in your life. It has an effect on absolutely everything else.
Chryst, I hope you feel better soon, dude.