from my jits experience, im not even sure there's a hold you can do that would break someones arm while pinning it to their back. that doesn't even sound like it's in your arms range of motion (or its range of not-motion, whatever). and besides that the kid wouldnt have the strength to break your arm unless you're absolutely scrawny. it's harder than you think.
I think you dramatized a little bit.
either way the kid that went apestuff over a game is clearly a friend so yeah. probably best to call him out on it a few dozen times and then not hang out with him anymore.