Often, we think bullying happens only in schoolyards and do not recognize that the perpetrators could be family members, be they parents, siblings, spouses, sons/daughters, etc. The traditional Chinese way of dealing with family conflicts is: "Oh, they are your family after all. They love you. Make amends. Blood is thicker than water." I would submit that if this works, fine. If nothing happens, perhaps a new approach is needed. Here are some thoughts:
Bullying is very much a power play. The new theory to stop being bullied is to let the person know clearly what are negotiable and what are not. Make the person know where you draw the line, beyond which you WILL NOT be pushed around and give in. In another word, a bully will keep pushing if there is no line drawn, and no clear understanding of the possible consequences (not to say you should make threats but one must be firm by expressing where one stands in a consistent and calm manner).
Generally speaking, we can end an "outside" relationship more easily and permanently than the one with our family members. However, there are no rules (other than those bounded by tradition) to say that a relationship cannot be adjusted when it is causing more harm than good. We do not live in a Walt Disney World in which "Everyone lives happily thereafter!!". Not all relationships have to be ideally "close". There are bonds between atoms. But when two atoms are too close, a heated nuclear reaction may occur. It is therefore up to the individuals concerned to find the optimal and healthy/tolerable distance. The objective is to stop the bullying so that no further harm will be incurred.
Bullying is not an easy subject to deal with, especially when it happens between family members. Emotions and expectations often blind our eyes and bind our hands to the extent that victims of bullying do not see a way out. Sometimes, it is better to walk away from a relationship and let things cool for a while. It will also give people time to heal and redefine the nature of a (sustainable) relationship. As they say: "If you love something, set it free. If it comes back, it is yours. If it doesn't, it never was."
It is your decision to make.
(Applicability: This article applies to bullying situations involving adults. Where unlawful, abusive activities are suspected or when minors are implicated, the readers should seek advice from professional counselors and/or legal authorities immediately.)