You should have turned into the right hand lane, and then carefully moved to the left lane (if that's where you needed to be). Sounds like just an angry person, acting the fool (road rage). Lets face it, there are a lot of idiots out there. Don't waste too much time trying to figure it out.
When someone is tailgating me (during the day), and gets too close to my car, I turn on my headlights, which makes it appear I'm braking because the taillights light up too, and people usually back off. (Not always, like I said, there's a lot of crazies out there).