The problem with that is that Elly doesn't want to be told what's actually going on because she hates being contradicted no matter what the cost to herself and those around her is. When she's got her mind made up about what the children are 'actually' doing, you'd better believe that they have to act as if they were actually doing something they weren't and make up for an imaginary crime because trying to tell her what's going on is bad and mean because they're arguing with her.
This leads us to the problem of those rare occasions where Elly can't avoid finding out what's actually going on and how far away it is from what she believed to be happening. Since she'd rather not admit to actually letting her fear of the children run away with her, it's actually the children's fault for not telling her earlier and sparing them the trouble because she's not the unreasonable, angry monster she actually is. Since she has no real vested interest in admitting that she made a career of losing her temper and turning into a screaming, threatening and abusive nitwit punishing her children in the most brainlessly unfair manner imaginable, she sprays a gloss of nostalgia over the past in order to protect herself. This is what can be called covering something in manure in the hope that something beautiful will grow. What it grows is a mother who doesn't learn from her mistakes.