It must be very difficult dealing with a son or daughters disability, a few years ago my youngest was hit by a car and was in a wheel chair for around a year and we found it hard.
My brother also has a severe learning disability from birth and has had a very difficult life. Then to add to these difficulties while under respite care he contracted a viral infection which was misdiagnosed as lymphoma for some time. Due to the misdiagnosis and not getting the correct treatment he ended up having a stroke, while in hospital he had another stroke and is now paralysed and will spend the rest of his life in a wheel chair.
He has had to deal with words like "retard" his entire life and while he is now 40, he only has the mental age of a 7 year old, he still understands what words like that mean and finds them very upsetting.