Your BPSO doesn't need to cooperate for you to set boundaries. Boundaries will change your life. It will get better over time. Without boundaries it won't get better over time. They are that essential.
Boundaries are lines that separate objects.
In terms of people and human relationships, boundaries are invisible lines that separate people from each other. Their purpose is to help keep us safe. Boundaries come in many forms and protect various parts of us. These include physical, emotional, spiritual, financial, and relational. For instance, what is appropriate between a husband and a wife is not appropriate between a mother and a child.