Hey mate, I'm really sorry to read you're having dark moments. I know how overwhelming they are and can deeply affect the psyche to the point of hopelessness, restlessness and discontent. I'm glad you're speaking in here and asking for help, that's often the most difficult step to take. I know it's been quite a journey to your present day and I applaud you for your honesty and bravery. The great thing about this process is you get your feelings back. And the worst thing is you get your feelings back!
Apologies if you've already spoken about this but is meditation a practice you've tried? It's really helped me in times of overwhelm and set a solid foundation for other practices I use to help regulate myself. I used to pass it off as woo without understanding the practical benefits. It doesn't have to be an hour of complete silence trying to clear your mind, dressed in ancient Asian garments. This video was first suggested to me by a mentor and despite first impressions, it was a genuine game-changer. Plus it's only 2.30 minutes! From this starting point I now use the Calm app (paid subscription, obviously plenty of free online resource too) for either guided or timed meditations. 6 years in I still struggle to do anything over 15 minutes daily and often my head is still going during it, but I almost immediately feel the benefits:
https://www.youtube.com/watch?v=92i5m3tV5XY
I'd also recommend Reasons To Stay Alive by Matt Haig. It's his personal story battling with depression and an anxiety disorder and a really easy and uplifting read;
http://www.matthaig.com/books/reasons-to-stay-alive-2/
Therapy helped me greatly too. I stumbled across the right person for me at the first try, which is unusual from accounts of people I know, so may need some perseverance. Like meditation, I was pretty anti-therapy until I tried it. Now I will happy-clap the brick out of it to anyone considering it.
Echoing Chich, if you are able to move your body in some way, get active. The endorphin release is free therapy and keeps your mind and body active. If you're struggling to leave the house, yoga or calisthenics is a great option. I use DDP Yoga, a great programme that combines the two and has helped me get fitter than I've ever been.
Keep talking my friend, there will be times of pain and overwhelm but doing as you're doing, being vulnerable, honest and looking to develop strategies to counteract those moments, will pay dividends. Small, simple steps create a bridge back to manageable thinking and living. Drop me a message anytime if you ever need to chat.