The resentment, of course, will be blunted by her remembering that her parents and older brother do the same thing to Mira for the same reason; as she sees it even now, they're trying to save face by ascribing Mira's total lack of concern if she's ever payed back any of the money that she volunteers her daughter to family politics because they don't want to have to admit that they envy her her generosity of spirit, that the defect in their personality that makes them so cheap makes them so ashamed of themselves that they can't even face it. Too bad for her that they're on the level with that family politics bullshit.
Since they are on the level and since she doesn't know, she's fated to not realize that when John and Elly reinforce her need to be a twit, they aren't doing so accidentally. That's because one of the things that I've noticed (and that she can't because she's too close to the situation) is that the Pattersons don't admit to their violent hatred of certain people; most of the time, they delude themselves into thinking that they pity the targets of their wrath. When I contrast April's open dislike of Becky to John and Elly telling her that she should feel sorry for someone who's thrown away everything worthwhile in life chasing a destructive illusion, I find that April is the least annoying of the hating haters who hate. She may have just as lousy a reason for hating Beckers as her folks but at least she's honest about hating someone; she's not going to disguise her envy and contempt as feeling sorry for someone that she'd like to shove off the planet for making her feel small about herself. Were she, of course, to know that when her parents say that they feel sorry for someone, they usually mean that they want to see that person be destroyed for their deliberately reminding the Pattersons of things about themselves they hate, she'd wonder if she was ever going to be an adult; it's bad enough that she herself had to lie to her beloved Grandpa because she was told never to admit to why she disliked someone without the damaging discovery that her parents aren't really the mature, loving but distracted and confused people she thinks them to be.
Once she's away from them, though, she'll start to wonder "Why didn't I accept Becky's attempt to reach out? Why was I so stupid? Why did my parents think that Becky cried herself to sleep every night when she got a lot of fun out of life? Were they even more envious of her that I was?" She'd also start to notice that the reason her mother envies Thérèse so much is that Elly not-so-secretly wished that she could throw away her children when they got to be a drag. Not, of course, that that would have made her happy; nothing that Elly does ever satisfies her for long.