Thanks guys. I'm ok, just felt my own height at zero speed, hurts a bit but really nothing serious. I just was waiting at the light when the truck came (very slowly, fortunately, otherwise I'd be dead right now) and rear ended me. He thought there was a green light and cars were moving - my opinion is he probably felt asleep...

I calculated that, lowest possible estimation for replacement of damaged parts, there was worth of 2150$ destroyed...
Gonna have a hard time make the insurance pay...

As for the KCNC Seatpost, I think it is ok to use it. I had no problem with it, the previous owner had no problem with it. With this accident that warped the rear triangle, the seatpost only developped about a 0,1mm bend. I'll have to replace it as it is an "ultralite" part of ultra-stiff Scandium aluminium which doesn't tolerate fatigue a little bit, the top tube probably has been slightly warped too in the process, but I think that under normal use there's little chance that you'd run a 6 tons into it. So I'd consider it safe enough to use, but I'm no expert. The original thick seatpost probably is safer anyway.