Panel 1: At the dinner table, John uses the laughably-inappropriate short form of Elly's name in order to try to explain that what happened that day was bound to happen sooner or later. Children lose glasses or bust the frames or scratch the lenses. Since calming down "means" that her feelings are horse-shit and she's this big idiot who isn't allowed to think for herself, she ain't having it.
Panel 2: Elly will not de-escalate because, as I said, that "means" that she's a helpless victim who has to be attacked and take it. This is why she makes that stupid remark about how since Liz has only had them for three weeks, Elly believes that this means that they'll have to buy them in bulk because Liz has "proven" that she cannot be trusted. This is because Elly thinks that since she never learns from her mistakes, no one else can and losing glasses will just keep on happening forever because crazy women and four year olds have trouble understanding How Things Work.
Eventually, this leads to her bolting over to Connie's for coffee so she can whine about how her children say cruel things that hurt her about how she's this unyielding block of granite who has all the warmth of a cinderblock and also comments from bad people who hate her about how she's a twelve cylinder whackmobile who can't understand what learning lessons is.
Panel 3: As Elly goes off somewhere to feel like she's the victim of all victims surpassing all others who have ever lived or ever shall live, Liz tells John that she's sorry and didn't meant to lose her glasses. John knows this and says that Elly doesn't understand because she's never worn glasses.
Panel 4: He gets all conspiratorial-sounding as he stage-whispers "She's one of THEM" which is meant somehow to include Liz into a sort of minority group or something. This is because he tends to carry the weight for the little missus and also wants the kids to respect her and doesn't thus say "She's totally insane."
Summary: The problem is that even when Screaming Insane Idiot Elly does require eyeglasses, her mind's eye is still really God-damned myopic. When this sort of thing happens to her, she's not going to look back and think "Gee. I was really unfair to Liz" because she can't put herself in another person's shoes. It makes her far less special, you see. Vanity does, after all, erode one's ability to empathize with others.