Some things that might be helpful to you, in no particular order:
-Look at David Allen's book "Getting Things Done" for getting organized and putting a loose general system that lets you feel un-overwhelmed. Very important if you've got lots of random to-do's that are overwhelming
-Look at Josh Waitzkin's book "The Art of Learning" - start to understand deterministic and incremental learning. Incremental learning sees success and failure as a result of gradually putting in training, deterministic learning sees things as a result of how good/bad you are. Incremental learning is empowering, deterministic is disempowering.
-Have a listen to Tony Robbins' "Get the Edge" audio program - it was recommended to me here on Hacker News, and I was never into that sort of thing, but it's really good. He'll give you ideas on how to start an exercise program, start setting goals, etc. You should start walking at least 15 minutes a day.
-If you don't have an iPod or other mp3 player now, beg, borrow, scrap, and scrape to afford a very cheap used model. Get some inspiring podcasts or audio books. Listen to them while doing errands or exercise that's boring. I hate doing mindless stuff, but it's a lot easier to get into a very good flow about cleaning, exercising for long periods of time, or running errands when you have interesting things to listen to.
-I also like Brian Tracy's "The Luck Factor" on audio, it describes all the attitudes and mindsets that produce generally positive outcomes, what most people call luck.
Normally I'd never advocate this as I believe in supporting content creators, but if you have literally no money and are on the verge of losing your mind, maybe go get a bittorrent client and download all this stuff. I think the creators will understand in this instance. Buy it later if you want to support their efforts, which you should with how much it can help you. Don't do this if it's illegal in your country or it seems wrong to you.
Good luck. The answer is to take small steps and celebrate the wins. Every minute you spend in nature, doing light walking, reading and learning the skills you need to dig out, progressing, and building yourself up is a win. Celebrate every time you have the meal you want to eat, wake up on the sleep schedule you want to be sleeping on, go for a walk, go to the library, make a phone call to someone, or so on. I've been to the depths of hell a couple times, you always come out of it much stronger. But the only way out is small steps of fundamentals and celebrating the wins. Don't get yourself down for not being perfect, celebrate every time you eat well, exercise lightly, handle your errands/priorities, stay focused on what you want, learn something, and otherwise take good action. That's the way out.
Finally, think about taking some martial arts. If you really have no money, tell the martial arts studio that you're very serious about training, have no money, but you'll clean the studio and run errands for them if you can get an occasional lesson at a mostly empty class. Tell them you're willing to do whatever it takes to contribute to the studio until you can afford your dues. Martial arts is good on lots of levels. Normally I'd recommend a scientific, military-based martial art to most people (like Krav Maga), but you actually might get more mileage out of Tai Chi, Kung Fu, or something with a spiritual/philosophical element to it.
Good luck. You'll get out. When in doubt, keep moving forwards. You'll be stronger than the vast majority of people once you come out of this, because you'll know you were at the bottom and survived. Nothing will be so scary after this. Prosperity! Claim it. Small steps. Be creative, celebrate the small wins, and you'll be back as fast as possible, and then ready to thrive even further.