Well, if you're looking to express some deep felt sadness over the internet it's a lot more tricky than in person or on written paper. You have to have the words to convey that sadness without going over the head of your desired audience.

The words you want are power words. Words that when you read them make you just want to break out and cry or what ever the desired effect. These aren't words that you use everyday. They can't be. They don't have powerd because you use them so much (yes, this means that curse words don't hold much power). To see examples of power words look up some well written poetry. Robert Frost has some good ones.

Once you have an idea of the words you need to determine what you want to say. Why are you writing these feelings? Who will read them? What do you want them to feel? When emoting sadness you want to think in a semi-dramatic scene. You don't want too dramatic that kills the credibility of the emotion.

As you write you need to employ images. Give your audience something to relate to. The easiest thing to relate to is disappointment. Being disappointed makes someone sad. You raise their hopes only for them to be unrealized and never fulfilled. You put that beauty before them and you take it away before they can reach it. The images also need to be painted in cool colors in their minds (greys, blues, purples, over cast days etc.)

You told me you loved me and I, being too quick to trust, believed you. Now, I sit alone in the dark of my empty apartment, too sad to move and change the burned out light bulb. I walk in the cold forgetting my jacket not caring enough to be cold. Have you ever felt this way?

Has your life ever been so dark you wish your mind had a flashlight or a candle to light your thoughts so you knew where they were going? Wishing you could see where they went so you could avoid the cliffs they tend to jump off; killing the small semblance of positive mood you had worked for hours to create. Cursed thoughts! The thoughts of you creating mirages and drawing them near to the edge, hiding it until it's too late and the end has come. Then the mind freezes in the dark icy water of emotion; drowning all heat and hope. Have you ever felt that way? If so, how could you exile me to such a place of emptiness and sorrow?

I had one of these experiences just yesterday. I found myself staring out my wind at the dark, overcast sky. Someone walked by minding their own business and you were there in my mind. What a joy it would be to see you near my apartment again. How wonderful it would feel to wave at you and see you wave back. Then the fall: you wouldn't walk by. You don't have to walk that way if you walk at all. The tears came to my unwilling eyes and I retreated,completely overcome by my disparing, to the dark recesses of my room. Maybe I will come up for air again soon and have a hope that there will be a face waiting to smile at me to brighten my day. Who could say? Who would say? Not you. "Someone...someone help me" I plea. Alas, it falls on the deaf ears of the room and I cry alone until sleep blessedly comes to relieve me of my pain.