@sensibleKitten1753
What happened to your sister is awful and heart-breaking and its very noble of you to want to help her. I think you should keep talking to her about going to therapy because you are not a professional and will not know how to deal with this healthily nor will you know how to protect yourself from all the emotions and turmoil your sister is going through. As professionals, they are trained to deal with people who have strong emotions and painful experiences, but you, on the other hand, don't. This could cause you even more turmoil than it already is to see and hear all that your sister is going through. And while you have not been through what she's been through, that doesn't mean that your emotional and mental health does not need protection and care. You owe it to yourself to protect your health too.
Please do understand that you cannot fix anyone. We cannot help people that do not want to be helped. You can help her look for therapists, you can go with her to appointments, you can book the appointments yourself but if SHE doesn't do the work, she won't heal. Sadness is an addictive emotion, it drives one down a rabbit hole and only one can take their own out of it.
I'm certain you're already doing a very good job listening to her and embracing her, otherwise, she wouldn't continue to come to you for support. But be mindful of extending yourself in ways that deplete you completely cause it could unfortunately lead you to resentment, and you cannot operate from a loving place if there's resentment.
Kindly explain to her that not all therapists are a right match for her. Just like any other social relationship, we pick and choose the people who are right for us and not everyone will be our own cup of tea. She's probably discouraged by her previous experience but that doesn't mean that there's no therapist out there for her. She has a choice in this - she can reject therapists that she cannot connect with, but she shouldn't stop looking for the right one. Do also remind her that in a therapy session, she is free to talk about the things she wants to and refrain from other topics. No one can force her to talk about the details or anything she is not ready to talk about. Something with this magnitude will require compassion and patience from both sides. She has the power to heal in her own hands. Let her know that cause that might be all she needs to feel empowered to make a change.
Maybe initially you could help her find a therapist and go with her a couple of times until she can do it alone. Maybe she could even enrol in support groups that have gone through similar unfortunate and painful events - she'll learn that other people have gone through what she's gone through and they have been able to see and reach the light at the end of the tunnel.
Whoever did this to her doesn't deserve her wasting years of her life in pain and limbo. It's the oppressor who deserves to be crippled with fear and pain, not your sister. I hope one day she manages to take the power away from them and back into her own hands because she's worth fighting for herself.
My prayers to both you and your sister to find peace and growth and maintain the beautiful bond you both share,