I'll come right out and say it (and that doesn't mean I've never made judgement errors while driving). In order of importance:

1) You were driving too fast for the conditions.

2) Your group shouldn't have stopped in a corner like that. That's just asking for it.

3) Someone in your group should have radio'd you to tell you they were stopping; especially since they stopped in a reduced visibility area AND on a slippery surface.

Like I said, I've made mistakes too and I'm sure even XOC has...nobody's perfect. Don't take it personally, just learn from it. Glad nobody was hurt.