I have a friend who is a fire fighter. I asked him how he could handle it. He told me you get used to it.
Hubby retired after 33 years. He has the most cynical, deadly sense of humor I have ever seen. His whole crew was like that. In all the years he worked there was only a few calls that really bothered him. I could always tell when he came home and then would shower multiple times in one day. He told me about them when I asked. Other than that he never ever talked about the calls. When they were done they were done.