I have a best friend I have known since high school. She has also been best friends with my sister for around the same length of time. Generally, when either one of us has a problem, we have each other's backs.
My sister has been emotionally abusive toward me for as long as I can remember. It has taken me decades and massive amounts of therapy to counter the gaslighting that has made it difficult even to trust my own instincts. She remains belligerent, angry, and unable to accept fault to this day (she is 31).
I have finally come to terms with my abuse and have cut my sister out of my life. I relayed the details to my best friend, who was sympathetic.
Yet she maintains a relationship with my sister. When I confronted her about this gently, she said she has loneliness issues and needs people to be around, otherwise she becomes depressed. She also concedes that this is a problem she needs to fix.
This puts me in a weird place. I understand she might not want to get in the middle, or might've gotten conflicting information from my sister, and I know it is not my place to demand she end the friendship.
But I feel she could get any amount of friends to ease her loneliness, or go see a therapist - she refuses to do either - but I cannot choose another past. If I could have some help putting my conflicting feelings to rest, I would appreciate it.
Answer: I can see why your friend's choice hurts you.
I can see why she gave the feeble reason she gave - sort of. It would have been more respectable as, "We have years of history, and I'm not prepared to give that up on the spot," but, OK - it's her prerogative and she's in a "weird place," too.
I can see why you interpret this as her prioritizing her comfort over your emotional health. You're thinking, "My sister abused me. Why isn't this a no-brainer?"
But also I can see why your friend didn't leap to boycott your sister. For one thing, it took you "decades" to understand the abuse fully and to resolve to sever the tie. How much time has your friend had to form her own conclusions? Weeks, months? You had your process, and it's possible she needs hers.
Her being so close to both of you from a formative age means she's not just your buddy. She's the friend who's practically family, right? So the reckoning process she goes through might have an element of sibling-style loyalty to it, in which she deplores your sister's actions but preserves the bond.
That is, if she even sees your sister's behavior as you do: Gaslighting is by definition so subtle that victims blame themselves for their abuser's handiwork. Your friend might genuinely have missed or misread it, and justifiably - if mistakenly - be skeptical. She might have sympathized with you more out of love and loyalty than solidarity.
Your sister could be gaslighting her.
She can be your best friend in every sense and still not know what to do. As long as she doesn't minimize your experience, it's OK to be patient while she adjusts.