Rely on gf for emotional support?

Dear all, I just posted another thread on a different subject, but here's a more general question about a somewhat extreme situation.

I have a very unusual job where I daily (or at least several times a week) see all kinds of unthinkable human suffering. Really, really bad stuff. Sometimes I get the chance (sometimes a good chance, sometimes a longshot, sometime no chance at all) to save people from a horrible fate, including in some instances, a painful and drawn-out death (I am not working in health care).

Seeing all the suffering along with the psychological burden of being in a position where if I fail, people may die, if I succeed people might live is, mildly put rather tough sometimes. I am not trained for this psychological burden, I got the job offer as a result of my academic field of specialty.

Sometimes I wanna throw up, other times I wanna cry from the things I see. Sometimes I exhaust myself because I cannot allow myself to fail.

I neither can nor want to tell my girlfriend the full details of my job. But sometimes (only sometimes, not all the time) I wanna tell her I'm emotionally beat from the things at work and just lay in her arms all night until I feel better.

She's the highly emotional one, I'm the stable nonreactive one: How do I tell her that sometimes I need her emotional support without ceasing to be the rock, the stable man she can rely on?