It is really hard to tell what is happening in a therapy session from the outside. Maybe the psychologist isn't giving your ex great treatment or maybe you aren't getting the whole story. I think you have to let your ex take care of herself now because she is your ex. Even if she does have some BPD traits or even if she has the diagnosis that does not mean that all of the problems in the relationship were hers, nor does it mean she is too ill to take care of herself. A DBT therapist would suggest that you don't treat her like she is fragile.