Hi Happiness66,
Yes, my friend, I've been there. What has worked in my relationship is validating. Not trying to argue with her, not trying to change her mind. Just acknowledging how she feels, acknowledging in some sense that you understand her emotions or that there's some part of her emotion that you can understand.
This is from a very helpful book, Loving Someone with Borderline Personality Disorder:
Validation authenticates some aspect of the experience of another. It is finding one (sometimes very small) piece of a behavior that is authentically understandable to you and communicating to the other person that it is understandable. You don't even have to agree with them.
People with BPD often have self-constructs of being out of control, having a lot of emotional pain, not being able to tolerate emotional pain, not being able to do things that others can do, not having a sense of who they are. So if your loved one has an identity that includes thinking she is worthless and undeserving of love and you are constantly telling her that she is wrong, that she is not worthless, etc., she will become more emotional around you and may well turn to her relationship with the violence drug addict who actually treats her like she's not worth anything and sometimes tells her outright she has no value.
If your loved one believes she's worthless, and you say, "You're not worthless," you are arguing against her self-constructs. She will likely get more upset. Using validation, you would say, "Look, I know you see yourself as worthless. the fact is, you have done some things that have made you feel that way, and I know that your mistakes in life have made you feel bad about yourself. This is what I know about you, though..."
