If you'll pardon my diagnosing you over the internet, you sound very depressed. I've been there and it's difficult to deal with, but not impossible.
For one thing, you've got to take a step back and realize that you're distorting things quite a bit. For example -- "I have to lie ... to sell myself". You need to focus on your strengths, for sure, in an interview -- everyone does. But that's not the same as lying, and thinking of it that way is turning it into an all-or-nothing proposition. Either you are a perfect, all-knowing software deity, or you are a liar pretending to be competent while hoping not to be discovered. These kinds of all-or-nothing scenarios, and other distortions, are very easy to fall into when you're depressed. Or so I've read, and confirmed in myself and others diagnosed with depression.
In any case I would suggest that your first step (as in, today) be to hunt up a therapist or psychiatrist. After all what is there to lose by doing so? It's a challenge in and of itself, so you might mentally make room for the possibility that it might take a few tries to find someone who gets you. Also http://devpressed.com/ might be worth a look. But this thread, and that site, should be in addition to talking to a mental health professional. I'm not a doctor, I think you should talk to one.
Good luck, and if you want to talk, email me (in profile).
EDIT: I see xaa has also recommended you talk to a professional. I'll echo some of their advice, particularly that part of the challenge is the same as most doctors -- you're going to have to be the expert on your own case. That doesn't mean you have to do everything alone, but you have to recognize that they're going to stick with a standard playbook, and you'll need to advocate for yourself and work to discover what works for you and what doesn't. Also agree that therapy/psychiatry isn't a cure -- it's a mental tool box. But it can be a very powerful one. Best of luck!