It's part of the story, yes, it's something called an 'antagonist', something you attempt to provide in the form of a random internet white knight, for example. You also believe that would make for a better story than one of the characters that is already involved in the story, and knows the main character personally, which is strange, incoherent, and is an assumption that has no basis in any of the information that is provided in the game.
Your theories are not reasonable, you provide no reason as to how they're supposed to work, for an example you assume that Cassandra and Lainey are involved somehow, which is completely illogical and there's no evidence that would lead one to assume that they have any contact with one another.
You make up theories based on what I can only assume is schizophrenia, I provide a logical framework to explain the things that are happening provided the information we have access to, you make wild assumptions that are nonsensical, and have no evidence to back them up, and are from a storytelling point inferior as they both remove suspense, character drama, and force the introduction of new characters where they are unnecessary.
There literally exists no reason to suspect Cassandra, the fact that Helen (potentially) spied on MC banging her solidifies my point that she is an antagonist in the story.
As to Helen being a "cunt", it is not my conjecture, she is objectively a fucking cunt.
