The Sin of Sucide?

According to Bible.com, it nowhere in the Bible directly says that suicide is a sin. Many feel, however, that due to the sixth commandment, "You shall not murder", suicide is an act against God.

I can fully understand the reasoning to this. According to Christian belief, our life is a privilege, one that God gave to us, and that we must serve and protect the holiness and condition of this gift. Many also consider suicide a selfish act, the selfishness a sin in itself.

I believed in this fully with every ounce of the fear in God instilled in me as a child. I could not kill myself. I did not see reason to. It was giving into the devil, and I would burn in hell without a doubt for such a sinful act.

But now, I do not think I truly believe in suicide being a sin any longer, or at least not with a 1/100th of the belief I once had for it.

When I was nine, I had a bone tumor in my spine, having to be in the hospital for weeks, multiple horrible surgeries ensuing. I immediately at nine had my life-expectancy put in front of me, the threat of death real. I questioned what god was doing to me, why he was causing all this pain, and for months and eventually years I began to have thoughts children my age should never have: why are we here? what is the purpose? will my family die soon? etc, etc.
In this came the bud of my depression, slowly taking over me.

And then it happened again, on my twelfth birthday. Another tumor that had eaten most of my leg.

I had by this time accepted what had happened to me as a test of God, but I was beginning to doubt. Then, a few weeks later, they realized I had another massive tumor, in my ovary.
I still tried so hard to believe, so hard to keep my faith, to keep the bad thoughts away. I remember the first time my depression hit me: I was in rehab, lying on bed taking a break. There was a cup of water only a few feet away, and I tried so hard to grab it. I put everything in standing up and trying to walk over. I knew if I could do it, would be okay.

And I couldn't. I fell back, and cried, and let the depression take over every part of me.

From this, thoughts of suicide eventually came. If my body wanted me to die so much, which it obviously did, why didn't I just let it? I had no more will to fight.

With that in my recovery, I was left alone. For hours, for days, for months. I had been sick during the school year, my parents working and no one to visit. It was literal torture, every day I would sit in the same chair, staring out the same window, slowly becoming numb.

I'm sorry, but if you have not had depression, serious, torturously painful depression, I do not believe you can understand. I understood then.

Is it really such a crime, if we are simply given things we as human beings are not equipped to handle, to follow the right thing to us, and let the pain go? Like a child dying with cancer, his/her body not given the ability to handle and fight the destructive tumor, some are given a type of grief that their minds can not overcome. Both may desperately want to live, and let me tell you then I wanted to live, be well again, more than anything but I could not simply do it. I was lucky enough to be given an advantage of special care, a benefit like camouflage that kept me alive.

I also learned my uncle killed himself, not died in a car accident like I was told for years. He was a saint, one of the least "sinful" people I knew. I honestly would send myself to hell to send him to heaven, for he deserved it more than anyone else.

Is suicide really a sin? Or more like an illness, like the depression itself? I know there is no real answer, but as a God fearing person, there needs to be more insight.