Much like many people say, when you voice something it becomes more real to you, well... that is true of writing also, which is why clergy, psychologists, good friends, all tell you the same thing: write it down. But here's the problem: they then say "read it, then throw it away." It's true, they say that. I've been told that myself, and I know a lot of others who have been told the same thing.
I don't agree with the last part, because that would be like saying: Okay, here is a book on the history of the world. Read the story once through then throw away the book.
Why I think people say to throw it away is to enact a kind of ritual. You see, if you throw it away after you've written it, it is supposed to mean: there, I've said it, now let it go, forget it forever, and move on. While that sounds pretty and appealing, it may not be
However, that is a disaster because you may not recognize that it is the same problem only in a variation, but the same problem nonetheless! Only when you have some semblance of it as a reference point, it may help you recognize a pattern, and you can deal with it much assuredly. You might even be able to rid yourself of the same mistake over and over, once and for all. Although, it does not always work, it works better than the other way; just throw it away and forget about it.
Getting back to the point, all of us go through things that sometimes hurt: we lose someone we love, whom we had a fight with, before they died, and we did not resolve the pain of, and resolution to, the matter. Or maybe we fell in love--with a person who could not quite understand what you were trying to convey in some part of your character's belief system, or you have issues with certain aspects of someone else's character. Or maybe you just cannot deal with certain issues, and although you've tried, you will never be able to deal with those certain aspects in life, because it makes you sick, or sad, or lost, or just plain mad; or it takes you down deeper, darker paths. Whatever it may be, we sometimes have to look at it again, and really analyze the issue.
If you write it down and throw it away after, you may remember, but then you may not. And if the same situation comes about, you may remember how to deal with it, or you may not. But if you saved what you wrote, you will consider that the present problem looks familiar, and once referring to your past writings, you can tell yourself whether you wish to go through this again, or not, or whether you can change something you hadn't thought of before that may give you a different result. This sounds reasonable to scientists, architects, engineers, and even doctors and lawyers...artists, sculptors, shall I go on? So, why not your average leyman?
Life is hard, there is no doubt about that--ask anyone, they will tell you the same thing. So we have to try and find ways to make it just a little more comprehensible, imperturbable, meaningful... We have to be able sometimes, to look at something again, and re-consider it, revisit it, RE-DECIDE if its potency, or its annoyance, or whatever the heck it did back when--is still the same or is it worse, or... you can plug in anything you want.
The trouble is, most people want to throw it away because they really haven't dealt with it. All they've done is look at the pain it brought, then vomit it out--thinking it's gone--and it is! (for a while). But if you didn't learn from it, and remember what you learned, you are more likely to "vomit again, and again, and again, and again..." Isn't that the fascinating thing about life? If you did not learn a lesson the first time, it'll keep coming around again, until you learn the lesson.
Buy a journal. Just a thought.