The Sextuplet Syndrome (Possessive!Matsus x Reader)

WARNING: THIS STORY CONTAINS MATURE THEMES OF DRUG USAGE, SEX, MENTAL ILLNESS, ADDICTION, VIOLENCE, ABUSE, ASSAULT AND MAYBE EVEN STRAIGHT UP MURDER. PLEASE DON'T READ IF YOU ARE SENSITIVE TO ANY OF THESE THEMES!
You are one of the six brother's closest female friend, a professional gamer and absolute anime fan, making a living off of your streams and presence alone on the internet. Through your streams you had met the brothers, befriending them after nearly no time at all.
Having known them for four years now since that day, you've all bared your souls and opened up to one another. No secret has been untold between all of you, that is, until a small accident during a get-together reveals that the sextuplets have been hiding a dark secret from you this entire time.
In an attempt to uncover more of this secret and finally fully understand your friends, they start to act strange, breathing down your neck at nearly every moment and following your every move. The more you know, the closer they are to losing you, until every person you associate with becomes a threat. The secret they've kept locked away slowly baring itself through you questioning mutual friends and acquaintances. Their love for you driving them insane, they see no other choice but to take fate into their own hands in an attempt to secure a future with you in hopes of you returning their affection.
Will they bind you to them, stuck in the nightmare of this curse they were born with, or will you be able to save them from their darkest fears in an attempt to save their downfall?
Or will they destroy everyone else you love before you even get the chance?