Please help me understand what was going on here with my mum?

My mum told me that she’d never have spent the amount I’d spent on my end of year party dress ($245, which I paid off on afterpay); and that she wasn’t trying to criticise me and wasn’t upset, just observing that she was raised differently. That her family had no money. She added ‘You’d probably spend thousands of dollars on a dress if you could afford it, but I wouldn’t.’ Then a few minutes later, she broke a glass and it shattered all over the floor. I know she has depression and anxiety and also this year, I’ve had a stalker and then the plumbing system collapsed in our house, then my dad had his eye operation. My senses aren’t as good as most people’s because I’m autistic, but I sensed that there might be something else in that comment, some subtle resentment of some sort. What do you think it is?

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It’s not obvious to me what’s going on.
Please help me understand what was going on here with my mum?
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