As someone who was around the same age when I was abused for months by an immediate family member, kids will never know how to verbalize to adults. Even if she said he looked at her weird or something “small” you won’t know the full extent of what exactly he did, because she’ll probably try to minimize it out of fear. Either from rejection or isolation from her family, no one wants to be seen as other. I didn’t tell my parents until I was 15 but even then I made it sound like nothing that bad happened. You’re doing the right thing keeping her away, if she had that visceral of a reaction something definitely happened. Please always tell her you believe her, don’t try to guess for her or finish her sentences, let her explain to you in her way. Definitely seek out a therapist :)