More like this but under a read more because I'm a monster? it gets pretty dark. CW for abuse, CNC, and mental health themes.
I can't believe I have to say this, but it's absolutely ableist to break up with someone who suffers from Pathologically Sadistic Abusive Narcissism. Studies show that this may cause them to threaten to hurt themselves, which is distressing for everyone involved but especially your poor partner, who doesn't deserve to be driven to suicidal posturing just because you have a hard time tolerating things they can't help and are as much if not more a victim of. People with PSAN need help, not isolation. If you really care about your partner, you'll stick it out and stay with them no matter what challenges their condition may have you face together.
Instead of separation, most modern doctors recommend:
letting them do whatever they want
doing whatever they tell you to
taking whatever they give you
altering your body to be more to their liking
giving them all your money
helping introduce them to the neighborhood whenever you move
avoiding contradicting them
encouraging them to hurt you
praising them for hurting you
downplaying your pain to others
assuring them you'll never leave no matter what
reacting aggressively when someone suggests you leave
cutting off anyone who's a threat to your relationship
cutting off anyone they tell you to for any reason
only calling an ambulance when given permission
These simple guidelines should help keep them happy. Remember, PSAN and conditions like it* are disabilities! Be patient, be accommodating, and remember that they deserve someone who loves them unconditionally no matter what they struggle with. People whose neurodiversity causes them to act in an abusive way are people too. Your partner is almost certainly suffering even more than you are. Do you really want to deprive them of someone who loves them, when you may very well be the only one who can?
*including but not limited to Acute Misogyny Syndrome, Consent Blindness, Sexual Assault Addiction, Compulsive Domestic Violence, Obsessive Stalking, Aggressive Rejection Sensitivity, etc.