This is such a good question to ask!

Often we give significance to people out of habit, or because they have a particular role... such as sibling or mother... but when one looks at their behaviour we see their is nothing sisterly or motherly coming from them, they are persecuting you, they are actually full of malice, and we just didn't want to notice! We are staying out of good faith... but that will only give such people the opportunity to cause great harm... speaking from my own experience ...

Answering the question for myself, they matter while we make them matter.

It's a different story when you are a child and dependent them.

But if you provide your own shelter, food and other necessities, their emotional and spiritual derangement which is expressed by their calculated acts of sabotage, is definitely grounds to cut the ties that bind.