I think definitely helps to talk it out. A few years back I was at the gun range and a guy attempted suicide in the stall next to me. He didn't succeed, believe it or not, but it was still fairly traumatizing and it wasn't nearly as bad as what you saw. I was more disturbed by the whole thing than I thought I was. It wasn't until after a few days I realized I was normal again.

Also, there's no shame in talking to a professional. I was fortunate enough (because he had great experience) to fly with the CA of a flight where a ramper walk into the spinning prop. He said he knew it wasn't his fault (which is wasn't) but he realized that he needed help.