FWIW, a (late) colleague of mine, as well as being a SAR professional and instructor, was trained in body recovery and was often called on at all hours of the day to perform those duties for the constabulary.
Talking to him one day, I asked him how he coped emotionally with these sometimes gruesome task(s). His response: "First of all, I treat each one (recovered body) with respect. Secondly, each one is treated as though they were still alive and care is taken that no further damage is done. That way, I can say, with my hand on my heart, that I did the best I could for that person. If I can help return the person to the relatives with not an extra mark on them, I have done my best." He had the same attitude towards first aid. He slept soundly at nights when there were no interruptions.
To anyone whose efforts in first aid do not have a desired positive outcome, consol yourself with the thoughts that you did everything you possibly could for that person. It was beyond your power/capability/training to do anything further. That they did not make it is no reflection on you, your training or your ability. That is life. Sometimes life sux.
Regards,
Le Vieux