You might find this helpful
Understanding dissociative disorders [link]
I understand how scary it can feel, especially as right now you aren't conscious of the splitting and dissociation.
I have a trauma related dissociative disorder this thread
dissociative distress thread *Triggering (Abuse)* [link] explains things a bit more. Other folks here who dissociate have also contributed to the thread.
I am a member of an excellent Dissociative Disorder and PTSD support forum for survivors of abuse and trauma. You might like to have a look round there. It's called
A Mind's Journey [link]
I would ask your therapist for some more information next time, and, although it can feel scary, trust the process of therapy. It'll take time to understand some more of what's happening, and make connections. But you have support, and there are lots of people out there who deal with similiar. Keep talking to us too if that helps.