I don't know if you've already been doing this, but something that's helped me is to discuss my concerns about talking about the difficult things. Feeling shame, feeling fear, dissociating, going into denial, anything that I think might happen.
For example, my T and I have decided on ways to do grounding at the end of a session. She knows that I feel a lot of shame and will need reassurance about that. We've talked about coping skills and how I cope outside therapy. We've even talked about what I'll do if I feel sick while I'm in her room. This makes me feel safer, and it gives her a better idea of how to support me.
To begin talking about the trauma, I've always found it easier to read out from my journal or take some art I've done. I find it very difficult to just sit and talk, but if I can read out something I've already written or explain a drawing or collage, it's a bit less difficult.
It can take time to be ready to talk about what happened. Don't rush it if you need longer.