Fact: Elly seems to see every little thing that happens to her as a sort of combat to the death with implacable and heartless opponents who will stoop at nothing to crush her. This makes sense to her owing to her own childhood career as the neighbourhood thug.
Not only is this why minor bullshit arguments turn into ungodly rows that Mommy refuses to get over, it's why we used to see the recurring image of the house looking like a bomb went off. Elly's fevered mind can only see one of two things: a sterile show-room out of a magazine or chaos and anarchy so should one single thing be out of place, the house is a mess and she's failed and the Quality Women will simply have someone shoot her and replace her with a good mother and so on into her going nuts seeing chaos wherever she goes. This is also why she can't look at her own reflection without seeing a very ugly woman no one could ever love. This leads us to Foob Fact Number Twenty:
Fact: Elly isn't really aware of it but she's hard-wired to fixate on flaws and imperfections and cannot see what's good in her life. This means that she cannot be consoled because she thinks people who see the good things are trying to trick her in order to mess with her.
Since she thinks everyone's out to destroy her and there's something wrong with her brain that makes her see her tidy, humdrum life as a dystopic Hell, it's fairly obvious why she makes every little damned thing into a big God-damned thing. It's also obvious that said state of unreasoning panic is why she can't be bothered to care how her actions affect others. More on that next.