Oh, Emily, so sorry to read this. I hope everything heals well. I think it impossible for humans to pay attention to everything and we just can't prevent everything- even when we know in hindsight we could have done something. Don't get into a constant re-run of the accident because it's happened and now you just have to go forward.
My two small bike crashes were caused by inattentiveness / judgement. The hematoma on my thigh took a full 6 months to disappear- at one point it was the size of half an orange! So it may take time and we don't heal as fast as kids.
Good for all concerned that the girl is okay.
Hugs- Sharon
2016 Specialized Ruby Comp disc - Ruby Expert ti 155
2010 Surly Long Haul Trucker - Jett 143