I suffer from depression and anxiety due to my mum sleeping with my abuser. i have no support and my gp wants me to do cbt. any other treatments?

Follow your GP: I think your gp may be right on. However, other treatments might include family therapy with your mother (not your abuser), if she is willing, but don't hold your breath. Individual therapy may be best in this case to get started.

You also likely have: Ptsd. Your therapist should be empathic, caring and understanding. Beyond that he or she should understand abuse dynamics and betrayal. Solid psychodynamic fundamental understanding is very helpful. Once you feel strengthened through a supportive therapy, then you can incorporate cognitive behavioral techniques. This is my opinion based on thirty years of treating abuse victims. Practice spirituality as well. Yoga can be helpful and psychiatric treatment medications can also be helpful. Best wishes.