So sorry to hear about your tragic fall! Sometimes group rides can prevent one from seeing obstacles: distractions--talking with others (similar to being on one's cell), watching the person's cadence ahead of you! One time I hit the light rail tracks on Market Street SF and yeah, "Whoom splat!," I went down quick. So I kinda can relate to the shock factor. Too bad I couldn't gather up the track and put it in my pannier like one of your friends did with your cable as a memento.

Heal quickly my fellow cyclomaniac!

Put some neosporin on that cheek right quick!