Phil 1

Ouch, sorry to hear this and hope you made a speedy recovery. Get back on two wheels as quick as possible as the longer you put it off, the harder it will be to get your confidence back.

I'm going to play devils advocate and say I think you were going too fast for the road conditions. Although it's certainly not your fault, It could have perhaps been avoided to an extent. I certainly wouldn't have been travelling any faster than 5-10mph over what the vehicles either side is.
Although it's conjecture as you could have hit it head on if you'd have been going just a little bit slower rather than being swiped off. You'd have had to be going a lot slower to have avoided it altogether.

Good luck in getting better and back up, that's the main thing.