Holy shit! You were VERY lucky (and very unlucky in the same way but you know what I mean...)
I had similar 2 months ago - hit a slim but solid girder lying in the inside lane of the M60 (must have fallen off a lorry or something), it got flipped up by the front wheel, went through the floor, through the fuel tank and embedded itself in the rear suspension at 65mph.
Accident recovery guy could hardly believe it, comments of "it could have gone through your seat". Insurance co were really good about it as well so hopefully yours will be the same. Now go and buy a lottery ticket for tonight and some medicinal alcohol to calm your nerves!