WTF - my BFF is HPD - now what?

I’ve never really felt “confused” about a life episode before, but here goes. I’m a happily married man, in my 50s. Until a few days ago, I have believed I just happened to be in the unusual position of being close friends with an attractive, charming, quirky, and much younger female (“Dora”), who is also a manifest “train wreck” mostly due to her own bad decisions. She has burned through many friends, and even more men, with whom she is generally very promiscuous. I have become perhaps her most stable friendship, probably because I am probably one of the few men in her life who doesn’t have any interest in using her sexually - and because I am overly tolerant of her many issues, including encouraging her, reminding her of her good qualities, and generally feeding her demanding and fragile ego. In short, my inner “rescuer” has probably makes her feel better about herself, and the fact that I’m probably one of the only men who hasn’t tried to use her sexually, probably makes me a symbol of “legitimacy” in male relationships. and sense of legitimacy. For this, she lavishes me with inordinate praise, and overt proclamations of how close we are. Being too much of a “nice guy,” I have reciprocated the praise. But it has recently become awkward, and my wife mentioned it, for the first time. A few days ago, a therapist friend, who doesn’t know Dora, mentioned HPD, in connection with the many dysfunctional behaviors I described to her. I read/watched everything I could on the topic, and felt like I was being repeatedly hit with a ton of bricks. To the letter, she has every symptom listed. Since understanding this my perspective has completely changed about her, and rather than feel like I am her close, supportive friend, I feel like I am feeding and enabling her dysfunction. When I recently gave her the most subtle and polite message that her request to take a day trip together might not be comfortable for my wife, she went into a mini-rage, and tried to punish me for “not sticking up for her.” Now she is being extremely apologetic, and almost pleading for us to remain “best friends.” My whole “friendship” suddenly feels like it is dysfunction. I know it’s my responsibility for being here, and I wish I could gently create separation, but know it will create a lot of drama. Oh, and she is in complete denial that there might have mental health issues. And she once attempted suicide (for real, not just for attention). Is there any hope of a better resolution than a dramatic ending?

*mod edit*