My two cents:
Yes, +1 on keeping the window rolled up. You probably caught on to that by now.
Yes, calling 911 is a good idea, BUT your first priority is to keep yourself safe, and you pretty much did that. Call 911 as the situation allows, but I would not substitute fiddling with the phone and/or its recording functions to collect "evidence" at the expense of keeping on top of the situation. You mentioned the "tunnel vision;" a lot of things are competing for you limited attention/focus at a time like that, fiddling with the phone should be well behind keeping an eye on the threat and dealing with it.
You actually got a pretty good "training experience" - you now know exactly what it is like to be under threat, and yet you didn't get hurt. If you are ever confronted again, I think you are likely to not be as anxious/rattled, and better able to deal with the overall situation. A bit of inoculation, if you will.
No offense, but I find it hard to believe you could shut the door on someone and not know it...
Two thoughts.
One, the guy who "shut the door" - on himself - was the guy running down the shoulder that was closed off, going too fast to react properly, who had to screech tires and cut in. There is no moral obligation for those in the next lane over to compensate for his poor driving. You might out of "self-defense" to keep the clown from running into your car, but if there is a problem, it is the fault of the one who was making poor driving decisions and driving beyond the capabilities of his truck and himself.
Two. I have "sneaked up" from behind on people while driving a large red truck with flashing lights and siren, who still didn't realize I was there until the last moment -- and been a bit surprised myself once in awhile when a police car, ambulance, or fire truck seemed to suddenly appear on my six at various distances, never mind somebody in a pickup driving too fast on the shoulder. It is all well and good to pay attention to everything, but in heavy traffic, most of the threat is up front, and it doesn't take long for the situation behind you to change. Check six often, but if you are not changing lanes yourself, you are not closing the door on someone in the next lane over who is driving with his ego instead of his brain.