When you hold something in from others, and avoid situations that will remind you, you can't squelch what's inside. It eats away at you in your private moments, in your heart & your mind. The "woe is me" held private makes you feel so alone.
Talking about it & your feelings, sometimes repeatedly, airs out your mind. Getting an "awww you poor thing, I feel so sorry for you" justifies your feelings & makes you feel much less alone in them. It doesn't fix anything or make the problems go away, but it helps you deal with them rationally & realize we all have them & have to get past them even if you can't get over them. Knowing you have friends & aquaintances who understand helps you move forward.
As a friend of mine once said: "We're all in the same boat - - sinking together".