You wake up and you feel - what? Heaviness, an ache inside, a weight, yes. A soft crumpling of the flesh. A feeling like all the surfaces inside you have been rubbed raw. A voice in your head - no, not voices, not like hearing voices, nothing that crazy, just your own inner voice, the one that says 'Turn left at the corner' or 'Don't forget to stop at the post office,' only now it's saying, 'I hate myself.' It's saying, 'I want to die.'

It's true, isn't it, that each of us has two hearts? The secret heart, curled behind like a fist, living gnarled and shrunken beneath the plain, open one we use every day.

How can it be, I wondered, that we can be lying in bed next to a person we love wholly and helplessly, a person we love more than our own breath, and still ache to think of the one who caused us pain all those years ago? It's the betrayal of this second heart of ours, its flesh tied off like a fingertip twined tightly round with a single hair, blue-tinged from lack of blood. The shameful squeeze of it.

The conclusion I have reached is that, above all, dogs are witnesses. They are allowed access to our most private moments. They are there when we think we are alone. Think of what they could tell us. They sit on the laps of presidents. They see acts of love and violence, quarrels and feuds, and the secret play of children. If they could tell us everything they have seen, all of the gaps of our lives would stitch themselves together.

Because for most of us, suicide is a moment we'll never choose. It's only for people like Lexy, who know they might choose eventually, who believe they have a choice to make.

You wake up and you feel - what? Heaviness, an ache inside, a weight, yes. A soft crumpling of the flesh. A feeling like all the surfaces inside you have been rubbed raw. A voice in your head - no, not voices, not like hearing voices, nothing that crazy, just your own inner voice, the one that says 'Turn left at the corner' or 'Don't forget to stop at the post office,' only now it's saying, 'I hate myself.' It's saying, 'I want to die.'

It was September, and there was a crackly feeling to the air. I was saying something that was making her laugh, and I couldn't stop looking at her. It was a little bit chilly, and her cheeks were pink, and her dark hair was flowing around her face. All I wanted for the rest of my life was to keep making her laugh like that. Sometimes our arms brushed against each other as we walked, and it was like I could feel the touch for minutes after it happened.