Scared to talk about my thoughts with my therapist

Are you having intrusive thoughts? They're uncontrollable negative thoughts, that can be caused by CPTSD, that are often violent or disturbing including hurting yourself or others in graphic ways. These thoughts are extra challenging because even though you really don't want to do what you're thinking and, by definition, they're disturbing to you not everyone understands and it can be scary to have them and to be open about them. Your therapist should know about it and not be judgmental assuming they know anything about CPTSD but if you're worried you have an underqualified therapist you could try looking into a specialist.

Therapists are well trained about intrusive thoughts and they know they come with ptsd. For example, I think about stabbing my arm a lot. I dont have OCD - I was tested. But I do have very violent intrusive thoughts from my brain constantly feeling under threat

Sometimes I will write and give my therapist my journal to look over. Sometimes not saying it out loud helps