I once had a problem with unpleasant things like that, and the best thing he can do is try to ignore it and put it out of his mind.  If he starts to see or experience something he doesn't like, he should immediately think of something else, turn on the TV, whatever it takes to focus his attention elsewhere.  I'm no expert, but it really helped me and I don't have that problem anymore.

hey river,

If "being shown" means that he is seeing these images in his own mind? And, if he has no particular spiritual beliefs or religious belief system? Then is is a serious problem that is just not going to "go away".

Thoughts of suicide are generally from someone who is depressed. Depression can be from the living enviornment or from a chemical cause. Either way it is not to be ignored. He may need an intervention. Treatment by a phyciatrist or a medical professional after certain chemical testing, is in order. If this is not comming from religious convictions, or life stress that may change once his circumstances change, then it is imparitive that this be addressed before these thought exculate into action!