I feel trapped inside myself?

Thanks to those of you who make take the time to read this.

I've been struggling with depression for the past few years. A few months ago, I was hospitalized/committed for attempting suicide. My father was furious upon learning my intention to end my own life. He made it very clear that it would be a very selfish thing to do. I believe that is the only reason I am still alive today; for my family's sake, that is. I am eighteen years old, by the way.

I hate everything about myself. I hate how I look. I hate my mannerisms. I hate the way I walk. I hate the sound of my own voice. I hate the flesh embodiment of what I believe to be a waste of life. Most importantly, I hate who I am. No matter how much pain I may inflict upon myself, there is no ridding myself of my need for punishment. I do not deserve happiness.

The small portion of me that reaches for help is perpetually crushed by those who are confident that I simply need to "cheer up" and "not be so hard on myself". There are also those who are adamant that my current state is a ploy for attention. An ironic notion, in fact. There is nothing that I'd like more than to find a spot in this world where they cannot find me.

I see and hear things that nobody else seems to notice. I feel like the world is closing in on me. I need a way out, but logically, I know there is none. I cannot kill myself, but I don't know how much more of this I can take.