I can relate to what you are going to, all my life my parents always made smart ass remarks and sometimes downright mean gestures towards me. I have now come around and realised how horrible it actually made me feel each and every time they have called me a "dumbass" or the like. I hate my parents for it, and they still have not realised in the end how much it has affected me, my self confidence and how it consistently made me feel terrible about myself and I still feel like they sometimes put me down, and that is why I was so excited to go to college, I feel so much better now that I dont regularly get put down. I know every time I am called something derogatory I go on the defensive and either dont say anything or try my best to rectify the situation only make myself look like more of an idiot.
Even though I am away from my parents, I still feel like an idiot much of the time in social situations, as sometimes I dont think of what I am saying before it comes out of my mouth and I make myself look like a complete idiot. Im always catching myself thinking that im such an idiot/retard/dumbass for saying things that make me look stupid. I am serious, I still do it constantly and I feel like everyone around me thinks I am a complete idiot. Much of the time I feel the same way, I wish I didnt exist and sometimes want to just hide, yet other times I crave talking to people just because I feel so lonely and dont see a point to anything in this life.
I kind of get where you are coming from and believe me when I say, you are not dumb....I know you are good at something and I know I am good at something (being computers myself). Honestly I have never actually been "Good" at anything in my life EXCEPT computers. I know you can find intelligence in any person, even if they feel like idiots. I found my strength and you just need to find yours.