I'm going to say sorry for your injuries. It really sucks, I've been there, done that, have the medals. And you don't want to see my x-rays.
Pictures show IMO, a fairly predictable surface. Looks like tons of traction - so ya, you made a bone headed move. Don't do that. The fact that your buddy behind ya crashed bad too tells me you guys *might* have been going a bit fast and close (where was his "out"?) for a gravely, surface shifting corner. Ya, I call that a corner, not a bend.
But don't sweat it, don't let us get "under your skin" (har).
Just get better, and ride when you can. Good luck man,.