I swore at a little kid since he didn't get it.
I'm now terrified. Why did you have to swear on a little kid?
He is about 11, I was playing with his mother when he came up to me and complained that I should go away.
It sounds like you overreacted. Even if he was being rude, his behavior didn't warrant you swearing at him.
WTF? He can't even fucking understand me, how can he see why I would want to hangout with his mother?
Even if he did not understand you, it's still morally wrong to swear at a kid as they may mimic your behavior and end up swearing with other people because he used you as an example. I would recommend you go back to their house and apologize to him and his mother and explain to him that swearing is wrong and inexcusable behavior.