anger from incest

I'm just starting to work with my therapist on the trauma from incest and rape. I've been reading everything about sexual abuse. I have so much anger about everything. I'm normally not an angry person. Is this normal to become very angry and not know where it's coming from and how do you deal with it. I've OD and self harmed. It's overwhelming. I see my therapist next Tuesday so we can talk about this but I just wondered if the anger was normal.