Why this movie is so disturbing
Nothing scarier than the thought that your parents (especially your mom) doesn't really love you, and wishes you were gone. Or worst, wants you dead.
And most people, probably, have experienced moments when their parents were stressed, and secretly (or not so secretly) wished their kids hadn't been born. Even if only briefly.
That's an incredibly scary feeling to experience as a kid, when you look to your parents for basically all your needs, both emotional and material. And are so dependent on them.
This film taps into that primal fear/anxiety most of us experienced at least to some extent as kids. Making it disturbing.
The fact you literally wanted to strangle that kid pretty quickly doesn't help.
Actual matricide is of course the most extreme expression of the above emotion, and probably the most disturbing possible act/thought possible. Making the film even more disturbing.
The love of a mother for her kids is probably the most elemental and basic positive emotion in the world, and probably the core foundation for civilized society. Out of that love, to a large extent, comes a person's sense of security and self-esteem, and their ability to love others.
When that is negated/eliminated, you're left with a pretty bleak world. Which I guess is why the kid was constantly shrieking.
Very disturbing film. Don't watch it.