Disappointment is awful. Just bloody awful. Before it occurs, you fill with hope and trust, then in one instant, it can be completely shattered. Whether you have been disappointed by someone or even by yourself, it can be soul destroying.
For me, to be let down is one of the worst feelings in the world. Whether it happened at work, between friends, in a relationship, whether you ordered something revolting in a restaurant, it's upsetting. You are left with an empty feeling in your stomach (particularly in a restaurant situation) which can make you want to curl up in a ball on the floor and wish you were invisible. At least that's how it makes me feel.
In my case, I put my hope in someone very dear to me indeed. They convinced me with all their wicked charm that I should put my trust in them. Oh how gut wrenching it is to be left out in the cold. I was the one that gave them the chance to prove themselves to me (not the first chance I might add) and they crushed all my optimism. In the end I'm the one still beating myself up, thinking how moronic I was to believe the silver tongued rascal.
Oh, shit on it.