This certainly sounds like depression. Some people respond well to cognitive behavioural therapy, some people really don't, and other therapies are worth exploring. It can be a long slog, and it can get worse before it gets better. I hope you can seek help, and I hope you can stick with until something works.

If you and your doctor decide that anti-depressants are worth trying, be sure to do a formal review with your doc after 6 weeks. Antidepressants are not meant for long-term use, and alone they won't fix things for you, but they may help you find something that works for you. On that note...

I'd highly recommend exercise. It's a hackneyed recommendation, but who cares. It's also been criticised for lack of significant long-term effects. But that's missing the point. Sometimes you need a healthy short-term fix, and hopefully with enough of them you can boot-strap your way to a longer-term solution. Go running, cycling, swimming, play soccer, take up boxercise, lift heavy weights, whatever works for you. Get up and out, preferably outdoors, preferably with social interaction, definitely getting sweaty and panting heavily. If you can hire a personal trainer, that might help, since you pay them to make sure you Do Not Quit. If you can join a class, even better.

Sounds simplistic, and it is. There's no way anything I can say here could encapsulate the issues you're dealing with, and there are no panaceas. This is a complex problem, no doubt about that. I hope you can find a way out of it.

Good luck!