A moment of extreme foolishness

I hate, Hate, HATE, shopping with my mother. She drives me nuts.
This all stems from a time when I was 17 years old and she kept me waiting for three hours, THREE HOURS (yes you read that right) parked on a yellow line whilst she popped to two shops 'for a maximum of twenty minutes.'
She has no sense of time or urgency and she point blank refuses to think ahead about anything. I was very scarred by this incident.
Yesterday, I made the inexcusable, stupid, pathetic, decision, out of pity, in a moment of absolute weakness and stupidity of promising to take her to the supermarket this morning "for a bit of fruit."
What a mistake. It's like a child in a toy shop, she can't get things into the trolley fast enough. Well actually that's not quite true. She headed to the fruit and held up an orange to show me. 'What's this?' she said, and starts to pick up fruit before she has a bag to put them in and then has to put everything back until I find a bag for her. And so it goes on throughout the store.
Every single item has to be discussed. She asked for 400 grams of clams. When Jan buys 500 grams she says that's what she wanted. So Jan gives her ours and we move on but not before she asks the fishmonger where they are from.
'Shouldn't you have asked that before you bought them?' I added unhelpfully. And so it goes on throughout the store.
At the cash desk the cashier asks her if she wants cash back. 'Oh no thank you,' she says, but just as the cashier has finalised everything she says, 'I'll have £50 please.' The cashier looked at her in disbelief and so it goes on throughout the store.
Even Jan who is patience personified (she has to be going out with you - Ed) said, 'I'm going to scream in a minute.' And so it goes on throughout the store.
Never, ever feel sorry for my mother. When it comes to shopping she will wreak a revenge on your stupidity in a way that you didn't think was possible. You have been warned.