I'm stupid

I just did a phone interview and I couldn't get s simple simple programming question. My mind feels fuzzy. I feel anger, humiliation and dispair.  I desperately need a job, I have been unemployed for months and I can't seem to focus enough to just answer technical questions.  It's like I'm not good at this type of thinking any more or I have some creeping brain damage. All I can think about is living in the street .... it's like so many people ... out of work, then out of a home. And I feel stupid -- like I've been foolong them all along. I was never any good at this anyway -- why did I chose this as a career??  I'm an idiot.