I've experienced several scenarios that began like this. I assume the horn (which I can barely hear past my earplugs) will be inaudible through the closed windows of a car at any distance. Instead what I do is flash my high-beams whenever I get the slightest hint that they're not seeing me. On more than one occasion a car that has started to move slams on the brakes when I do that and an accident was likely avoided.
Honestly, I truly believe that if you could show on a screen what many drivers see when they're looking in your direction (no, not at you, just your direction) you'd see a motorcycle-shaped blank spot where you were.
Given the damage on the car I'd say it's a sure bet your bike is totaled in the sense the frame is likely bent. You've got a pretty sizable settlement coming your way from the driver's insurance, hopefully you don't have to take them to court. Given the nature of your injuries and the circumstances, I would seriously entertain the notion of getting a lawyer because I'm betting the insurance company's going to try lowballing you by $10-20 thousand bucks. Check out these guys:
http://www.aimncom.com/
And don't sign any medical releases until you're completely healed. Though it's possible to go back after them for secondary claims after doing so, it's a lot more difficult and expensive in both time and effort.
Glad you "walked" away from this one, over four thousand of us won't be this year.