Why is your SO comfortable being with this person, and why doesn't he have strong enough boundaries, or enough respect for your relationship, to not let it be sabotaged by her disorder?
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.