You were obviously watching him, based on your detailed descriptions of when he changed lanes to get behind you, how long he stayed there, how far away he was, and when he started to pass you. You probably could've avoided this "accident" if you'd wanted to, but he cut it too close and he picked the wrong person to try and bully. He wanted to be a dick and cut you off, and you wanted to be a dick and fight for your spot in the left lane and not let him get by. Whatever, he got what he deserved and one day you will too. We all will.