Hi Andrew,
From my experience this is so common - that might be a good place to start with your folks, letting them know how difficult this work can be and that it's not uncommon to feel the effects of trauma from simply hearing other people's stories. (My experience is that sometimes people feel shame or embarassment that they're feeling this way).
I've done a lot of training on this topic and one resource that I absolutely love is Laura van Dernoot Lipsky's book Trauma Stewardship. I recommend it to everyone I know and I have some training materials I've developed based on the principals in the book. Her TEDtalk is a nice primer on some of the concepts in the book as well.
If you think it would be helpful, please feel free to contact me and I can share more with you about the training I've developed on this: kaleigh@k-cornelison.com