At what point do I tell my child that life just isn't fair?

Alice O'Keeffe's "Squeezed Middle" column.

Squeezed middle.
Larry and I are feeding the ducks in the park when I spot something out of the corner of my eye. What is that? I squint and peer, and eventually walk over to the plastic bag glistening in the sunlight by the side of the pond. It is full of lamb chops. Raw, sweaty, slightly greenish lamb chops.
 
My stomach heaves and rage rises up in my chest. What kind of beast dumps a bagful of raw lamb chops in a public park? The same kind of beast that rips up the daffodils planted by local schoolchildren. The same kind of beast who lets their horrible slavering Staffie shit all over the children’s playground. The same kind of beast who is still drilling for fossil fuel even though the human race is headed for a slow, hideous extinction. What is wrong with humans? We seem determined to make life unpleasant for ourselves.
 
“What is that?”
 
“It’s nothing, bubs. Somebody has left some meat in the park, that’s all.”
 
“Why?” Larry is going through a “why” phase.
 
“I don’t know. People do strange things. Sometimes they do things that aren’t very nice.”
 
“Why?”
 
I have been wondering when and how to introduce Larry to the idea that people are often complete idiots. Brutal honesty is my new policy. Middle-class mothers spend too much time telling their children to be nice, to share, not to hit anybody, to say please and thank you, not to drop litter in the street, or tease cats, or stomp on worms. I feel we should prepare our offspring a little better for the harsh, selfish, brutal and misguided reality they will inevitably face at some point.
 
Yet, before I can say anything, I feel a tear trickle down my cheek and disappear into the collar of my coat. What is going on? I wipe it away quickly. But then there’s another one, and another, and before I know it I am crying, really proper snotty unstoppable crying.
 
“Mummy, what’s the matter?”
 
“Don’t worry, darling, I’m fine.”
 
But I’m not, that much is obvious because my mouth gapes and I have to cover it with my hand before I start to dribble. The truth is, I haven’t been feeling too good recently. Perhaps it’s because Moe hasn’t been sleeping, or because Curly and I haven’t been getting on, or because I’ve been trying to work too much, or because the house thing fell through and now we’re going to be stuck in our slightly-too-small-flat for evermore. I don’t know. I wish it would all just go away.
 
Larry stares at me, puzzled. He’s lost some of his baby chub and his features are starting to take on the more defined angles of a little boy. The thought that he will one day grow up sends me into another round of ribcageracking sobs.
 
“Hey, you know what?” He scoots over to the buggy where Moe is lying asleep and rummages around until he finds the stained and tattered rag he has been sleeping with since he was a baby. “You need blankie.”