The following, by Hellen Hignett of Divorcedmoms.com, is a good summary of the telltale signs/symptoms that you are dealing with an extremely toxic emotional black hole of a person, who has mastered the art of controlling and manipulating, and who does it because they can and they benefit from doing so.
Though the following characteristics primarily focus on romantic or marital relationships, please understand that they can apply to a family member or parent, a boss or coworker, a pastor or fellow church-goer, or neighbor. The closer they are to you, the more damaging they are, as they are among the best and professional of all manipulators, they are the white-collar psychopaths, who have elected to override their conscience so as to free themselves from any pangs of guilt or feelings of empathy. Simply put, they are a master manipulator, a selfish black hole person.
If any of the following seem familiar, then please understand that you are dealing with someone who:
(1) has spent years perfecting the art of who they are,
(2) is not suffering from emotional pain or a psychological disorders, and (3) has chosen to double-down on being the way they are because of the benefit they receive at manipulating and traumatizing those who dare trust them.
The only thing you can and should do upon recognizing these signs is to plan your departure and implement boundaries. Though the issue of divorce does not need to be decided at this time, you will need to implement a plan without first discussing it with the sophisticated manipulator, as he/she will only manipulate you once more, but also likely ratchet up the rhetoric, the manipulation, and the abuse.
If you are going to implement boundaries, anticipate that things will get worse. Plan for there to be drama in one way or another, shifting quickly from helplessness, to martyrdom, to guilt trips, to threats, to a revealing of who they truly were all along... a calculating and conniving individual who was simply using you for all you were worth, for as long as you were willing to be used and abused.
Please understand ahead of time that the Oppressor will not stand idly by watching his emotional slave get up and walk away into freedom. Rest assured there will be drama. He/she will become defensive, controlling, give tremendous "push back", and inevitably become incensed and irate because:
(1) you finally caught on,
(2) the gig is up,
(3) his/her ability to control you is likely slipping away,
(4) they derived secret satisfaction at being the Chess Master who was able to manipulate you, and
(5) they will now need to take the time to find another victim to target.
As such, it is recommended that you find a trusted friend to role play how things will go, and find a few people who can help you as you implement your plan of separation/departure.