Nonny you are 100% justified in calling her out tbh and I hope you have the support and safety etc to feel comfortable doing so if that’s what you want to do. She knows your ex is an abuser and abused you, and she’s deliberately telling you to essentially keep it to yourself because she doesn’t want to know? That’s pretty fucked up on her part. Saying she’s “scared to know” the details of your abuse is basically a tactic to obligate YOU to cater to HER feelings about YOUR abuse. It would be one thing if she said that because details of intimate partner violence is like, triggering to her, BUT she also cut the guy off, held him accountable as an abuser, etc in support of you - but that’s obviously not what she’s doing, it sounds like she just wants her social life to not be complicated or whatever.
Your safety from this abuser is more important than her social life not being complicated. This guy abused you emotionally and physically and you deserve nothing less than support from your friends and I’m so sorry you haven’t been getting it from her. I hope that whatever you decide to do you are supported by other people who care about you. I’m so sorry your ex did that to you and I’m sorry there’s even one person in your life who is pulling this “I don’t want to know but also I know but also I’m going to hang out with this abuser anyway because I don’t want to ~take sides~ or whatever” bullshit with you.
I know calling people out can be super scary and I think you’re being really brave. <3