I've certainly been right where you are, in the last 2-3 years. It's hell-on-earth that's for sure. I know that my depression can possibly be caused by not taking my anti-depressents for a time (& resuming them tends to rid the depression in a day or so). You really need something right now to take the "sting" out of the depression you are in. I would recommend anti-depressants for the chemical imbalance, and meditation, positive affirmations/quotes/words, inspirational images, etc for the mental side of the equation (as i believe depression is a factor of these 2 things - bio-chemical & mental/thoughts/beliefs). What's happening is your brain is hyper-focussed on threats, of all kinds, from all places .. and these threats are being highly exaggerated in your brain/mind. You need to change that. It's hard, as one's thoughts/beliefs create reality, and changing them is not easy at all. But it can be done. Start now. Start looking into what's out there (including "alternative" or "new-age") to help you now & longer-term. I'm sure i've recently come accross some free audio-subliminal stuff to help rid depression. And there is software like iDoser (virtual drugs; better for you than actual drugs). There's all kinds of new stuff coming out (if you know where to find them). And of course there is the age-old tradition of religion.
Here is a good quote i found to start with: "Nothing real can be threatened. Nothing unreal exists. Herein lies the peace of God"