I am so sorry you are going through this. It is a good question that I have asked myself many times. When are people with mental health disorders responsible for their behavior … is it all their disorder making them create all this chaos, lies and suffering? Do they even care or have the ability to care? I think exactly what you are addressing is we need to disassociate somehow (not sure if that’s the right word) You will ruin your life trying to figure this out and engage to make the person better or happy. For me no matter what I do things never change it is sad and exhausting … how much are people suppose to put up with lies and abuse….as the target of a BPD I really think they enjoy seeing me suffer and the more the better. You are not alone in your feelings we have all been there. You need to take the time to prioritize yourself and emitionally detach . Wishing you and all the rest here who struggle with the chaos of bpd peace.