The family dog

I suppose the single advantage of having a disabled child is that I can clearly identify the ultimate cause of my mental illness. It was like standing on train tracks, unable to move, watching the freight train approach and knowing that the only way to get out of the way is by abandoning your loved one.

For my wife & I, it started with the very difficult and traumatic birth of our second child, followed just nine months later by concerns that he was deaf. By the time he was 18 months old he was being assessed for autism.

Anyone familiar with autism (especially what is called the 'Low Functioning' end of the spectrum) knows what followed: years of smearing and eating poo; nappies shredded and removed before our son peed on the furniture; toys and personal possessions destroyed. Our framed wedding photograph went very early on. Thankfully that wasn't an omen. We got through ten televisions in one year, as he would attack them when his favourite programme finished. Six new kitchen ceilings after floods caused by destroyed toilets. Doors ripped off their hinges when he was 4.

The violence and destruction wasn't limited to objects, either. Years later our youngest son's rugby coach commented on how he is "not afraid of being flattened by much bigger boys." That's because he grew up with it. He grew up in a house that looked like a battlefield and where his brother's needs took up all his parents' time, his possessions were routinely destroyed, and sleep was something you tried to maintain against a background of wailing, shouting, self-stimulation humming ("stimming") and constant crashing and banging.

As if seeing our home trashed wasn't bad enough; as if being unable to socialise with a screaming, poo-smearing child prone to violent outbursts wasn't enough, as if being robbed of our identity as a family wasn't enough, the sleep problem did the job of breaking me.

It's not unusual for children with autism to need little sleep. Our son didn't need much, and even when he was tired he fought against it. We never found out why until he was about ten (he learned to talk at the age of 7, but it took another three years before he could explain something as complex as a cause and effect) - "If I sleep, I have scary dreams." He could keep himself awake for three days and nights, and then after just four hours he was good to go for another three days. And if he wasn't supervised throughout this time, he would endanger himself and his entire family.

So I would spend all night on a chair in his room - and then during the day go to work. I lasted three years before I was carried out of work in an ambulance.

This brings us to the child we forgot. How can you forget your eldest child, your only daughter? Well, we did. Everybody did.

As I was recovering from my first mental illness 6 years ago, we slowly began to realise that I wasn't the only one suffering from it. When it all began, our daughter was one of the brightest, most outgoing and active girls in her class at school. By the age of 9 she was silent, withdrawn, socially isolated and not eating or engaging with anything or anyone. Her new school's assessment was that she 'just isn't very bright' and we had 'unrealistic expectations.'

As with so many families of autistic children, social services and education repeated the easiest error of them all, and assumed that the effects of autism on the family were caused by parental failings. In effect, our daughter's school blamed us for poor parenting. This is not new: Leo Kanner (who first identified autism) made the same error in the 1940s and for 70 years autism parents have been routinely blamed for what this disability does to our families and held responsible for fixing it. It was Lorna Wing, in the 1970s, who proved that it wasn't the parents' fault - but even now an awful lot of professionals don't understand that.

We were lucky. I was able to return to work and pass my entire salary on to a fee-paying school which took our daughter and youngest son and provided them with the environment all children deserve. They stayed in the evenings for clubs and games, they learned to swim and dance and do all the other things children take for granted. And even though we couldn't afford it, the school saw when our children needed a good night's sleep and they gave them a bed in the boarding lodge, free of charge. Our children learned to laugh again, and our daughter's predicted GCSE grades this summer are considerably better than you would expect for a child who is 'just not very bright.'

As a family with a severely autistic child, we have had more than our share of good luck. Ten years ago my wife and I created www.asdfriendly.org which is a support group for carers of autistic children, and in it we have seen countless families suffer far worse mental illness, far more vindictive and dismissive responses from services that should help them but actually blame them. Parents have been accused of having Munchausen Syndrome by Proxy, families have been torn apart, schools have refused to provide appropriate help.

Right now, we are in a good place. Precarious, but good. I suffered a second severe breakdown 18 months ago, with about six months of suicidal thoughts, and resulting in a diagnosis of PTSD and a consultant psychiatrist concluding that I am no longer fit to continue in my chosen profession. Our daughter is still prone to withdrawal into uncommunicative depressions that can last months at a time. Our youngest son presents his symptoms more like his mother: dogged determination, ruthless singularity of purpose towards goals, absolutely no time for or tolerance of self indulgence or self pity. Our house still looks like an institution, with locking internal doors, wipe clean surfaces, an unkempt garden and broken furniture. It doesn't look or feel like a family home.

And we are one of the lucky autism families.