I have both diagnosis's as well. For the PTSD long-term therapy with a professionally trained trauma therapist has been extremely helpful and my symptoms are now mostly under control and even hardly noticeable most weeks. I have also had CBT and DBT group therapy which has given me many great tools to manage the PTSD and Bipolar. It is really important that the therapist and/or groups you go to are done by trauma specialists as I have had so many awful experiences with well intentioned therapists who only made my PTSD much worse.