I reckon had you been with one of the big logistic concerns they could well of had people within HR trained to deal with just a situation like this.
It doesn’t matter whether you see loss of life on the front line in Afghanistan, or over the white line in the hard shoulder. Its a traumatic experience. If it still bothers you its perfectly acceptable to speak to your family doc, to see if there is some form of counselling in the area.
Welcome back to the job by the way. 