Depression led to separation which led to desperation. Please help!

My wife and I are recently separated since 3rd Jan 2012, after over 10 years, 9 of which, though never perfect, I believed was beautiful and healthy. The joy of our relationship gave us 3 beautiful children; 7, 5 and 2. I've been dealing with depression unknowingly since late 2009, well before the separation, having memories of a dark history seeping into my head; including child abuse, death and mistakes I've made in life.

Clinically acknowledged in November 2011, with the guidance of my wife in seeking help. Since 2009, I've been carrying suicidal thoughts, never realizing I'd began to fall into the darkest of holes, no human being should feel or be in.
One evening, on 02 Jan 2012, during a conversation with my wife about our relationship she told me she has no love left for me, on the basis that over a year ago (Oct 2010) after revealing she kissed another man, she's been trying to build a foundation she no longer had with me. I forgave her and realised there was work we had to do to get the love we used to share back on track. I believe, in desperation that I smothered her with love and affection that only pushed her further away, also dealing with my personal illness. I also believe that the depression prior had unknowingly caused her love to shed away. I easily became agitated, indecisive, irritable, moody and withdrawn. On the evening of the 2nd of Jan., in my depressive state I attempting suicide.

Emotionally overwhelmed with self-hate and self emotional punishment. It was like I instantly lost all control of my emotions and took a bottle of sleeping pills and swallowed them. Let me make this clear. It wasn't only our marital issues that subsequently caused this nervous breakdown, it was a series of life events including sexual abuse that altered my mind enabling me to lose control. In the midst of this turbulence I read a ‘going away’ letter to my wife. I kept this letter with the promise to myself, to my GP and to my psychologist that when I wrote it some months earlier, I kept it as a device that whenever I'm in a dark place again I'd use it as a motive NOT to commit suicide, as strange as that may sound. But it happened. My weakened mind, this illness, this sickness, desperately called out for help in the form of taking sleeping tablets and reading this ‘going away’ letter to my wife. Letting the children know that since I've failed with the relationship with their mother, I've failed as a father and I failed in life, so I need to ‘go away’. Despite my committed love for their mother, she may find it better that I ‘go away’.

The honest reality is this letter was never to be shown, never to be read to another, or never to be seen by another. This rightfully shocked my wife and she called the ambulance and I was consequently taken to the hospital, monitored until the following morning. I was ashamed and regretful of my action, in disbelief that 15secs I was unable to control my depression and wanted to die. This illness, this disease took control of my emotions. It wasn't believed that full admission would be required. I did not have depression through substance abuse nor depression through any psychotic issues. Though one would seem psychotic when attempting self harm or death.

I have been continuously monitored by a crises team, my doctor and my psychologist. My wife brought clothes that morning in the hospital and told me she does not want me back home and felt she lost respect for me due to my emotional breakdown. She further requested a separation and needed space. I therefore was left alone and was bewildered of what just happened. My cry for help seeded itself in the form of an attempted death. My world, my wife's world and my children's world turned upside down. Its mow 25th of January and I still struggle to not blame myself. What to do now? How did this end this way? Is there any hope for my wife and I? It's obvious I needed help and still do, but I feel useless without my family. Please help