kd17, welcome
we're so glad you're here!
I don't really have any good ideas about how to present therapy as an option, but I might do so with measured expectations. It doesn't often go as planned. People who have BPD have a pretty deep sense of shame. Unless they're already open to therapy and have been considering it for themselves, it comes across as "you're so messed up you need professional help," no matter how lovingly you present it.
If it doesn't go well, or she refuses, don't despair. My person with BPD is my mother in law. She won't get counseling, nor does she have an official diagnosis but that hasn't stopped me from setting better boundaries and making changes that have impacted our relationship in a positive way. Therapy is a tool and there are other tools you can learn to use that will help.
Makes sense that your heroic efforts are detrimental. BPD's are sometimes drawn to people who can 'save' them. If you stop your heroic efforts, what happens? What does that look like and how does she respond?
