My adult dsd has some mental health issues. She has told huge lies in the past (terminal illnesses etc). She's so difficult we have felt a need to distance ourselves. We had a family event recently, she broke down saying she didn't feel part of the family. Fast forward to this week and she has made a disgusting allegation about her DF (my DH) at said family event. DH thinks the allegation more than anything else shows what a bad place she is in mentally and that she needs help. I'm not sure I can be part of it because I've taken all I can take. She mentioned years ago she was diagnosed bpd but I think it's worse. It's like she is a psychopath. How can he help her?