You have already rehearsed the conversation a hundred times. The version where you say it calmly. The version where they cry. The version where you say nothing at all and just stop answering the phone. None of the versions feel clean, which is probably why you are still here, still asking the question instead of acting on it.
Three thinkers on the Consilium roster would approach this from fundamentally different directions. They would disagree about what cutting someone off actually accomplishes, and that disagreement is the point.
Winnicott: the wound is old
D.W. Winnicott would not ask whether this person deserves to be cut off. He would ask what you built to survive them in the first place. Children who grow up with a parent who cannot reliably hold them, who cannot be trusted to respond to what the child actually needs, learn to construct a self that performs safety instead of feeling it. Winnicott called this the false self. It is not fake in the sense of lying. It is fake in the sense of being built for someone else's comfort rather than your own.
He would point out that cutting the person off does not automatically dismantle the false self you built around them. That structure can outlive the relationship. The real question is not whether you leave, but whether you can tell the difference between protecting yourself and simply repeating the same old strategy of managing someone else's feelings, this time by removing them instead of appeasing them.
It is a joy to be hidden, but disaster not to be found.
Hurston: walk away whole
Zora Neale Hurston would have little patience for the idea that leaving requires a philosophical justification. She spent her life watching people stay silent to keep a fragile peace, and watching what that silence cost them. Her position would be blunt: you do not owe anyone continued access to you simply because they share your blood. Endurance is not the same thing as virtue, and a family bond that requires you to keep shrinking is not one you are obligated to preserve.
If you are silent about your pain, they'll kill you and say you enjoyed it.
She would ask what your silence has been protecting. Usually it is not the relationship. It is an image, the family's image of itself, or your own image of yourself as someone who does not give up on people. Hurston would say that image is not worth what it is costing you, and that walking away whole is not the same as walking away bitter.
Girard: the pattern will follow you
Rene Girard would want to slow down before you act at all. His whole theory rests on the idea that people rarely want things on their own. They imitate the desires and conflicts of those closest to them, and families are the original site of that imitation. Rivalries, blame, who gets cast as the difficult one, these are not random. They are roles assigned inside a system, often without anyone choosing them consciously.
He would ask you to name the role you have been playing before you leave it. If you were the family scapegoat, the one who absorbed the conflict everyone else could not face directly, cutting off the person who assigned you that role does not guarantee the pattern ends. Without seeing the mechanism clearly, you risk finding or building a new version of it somewhere else, a new relationship that quietly reproduces the same imitation and blame.
Man is the creature who does not know what to desire, and he turns to others in order to make up his mind. We desire what others desire because we imitate their desires.
Where they disagree
Winnicott would say the decision to leave matters less than whether you understand what you built to survive. Cut someone off without that understanding, and you may simply relocate the false self somewhere new.
Hurston would say that is too much analysis for a situation that is, at bottom, simple. Some relationships cost more than they give back. You are allowed to stop paying.
Girard would say neither leaving nor staying resolves anything if you cannot see the role you were assigned. The scapegoat who walks away without understanding the mechanism often becomes a scapegoat again, somewhere new, cast by different people using the same old logic.
None of them would tell you what to do.
The question you came here to avoid
You searched this question hoping someone would grant you permission, or at least confirm that leaving would not make you the villain of the story. Permission is not really what is missing. You already know whether this relationship is costing you more than it gives back.
The harder question is not whether you have the right to leave. It is whether you can leave without carrying the same pattern into whatever comes next. So ask yourself this: if you cut this person off tomorrow, would you actually be free, or would you just be waiting to see who takes their place?