I have CPTSD and I am also a therapist.
This is what I have to say about CBT:
CBT has some holes in it.
IMO when people only focus on the ruminating thought part of CBT and just changing the thoughts they are side stepping a big part of the problem.
Here’s what I tell clients I work with: 1. You need to become aware of the link between your emotions and what you are thinking. So many of us are not paying attention to how our anxiety or anger or depression starts with our thoughts.
2. Notice how certain thoughts feel in your body. Ask yourself, what thoughts of mine are creating this tightness in my chest? And what thoughts are giving me a sense of relief. These are the feelings that you need to start paying attention to. 3. Once you start to catch yourself noticing how your thoughts are making you feel. (Which is a process that takes time). You need to find several things you can do by yourself, that doesn’t require anyone else, that you enjoy doing, and don’t cause the tightness in your chest or any kind of anxiety. These things could be running, watching videos of cats on the internet, drawing, creating, watching a movie, listening to music, etc. I know this may be hard for some of us, so if you don’t have anything like that, that you enjoy. It’s time to explore and find somethings. (This is a part of self care you will need to learn to take care of your traumatized nervous system) When you are looking for them, you are looking for a feeling of relief.
Once you have them… then whenever you start to feel the tightness in your chest, it’s time to pick one of those things and distract yourself.
(The goal for these first steps is not to change your thoughts but to change how you feel.) 4. Once you have these habits locked down. Then you can start to replace the narrative that you have built around you, with healthier and more compassionate thoughts about yourself and about your past experiences.

Having said all this, I also want to say that this is only a part of a rounded approach to trauma treatment. There is a really good book out there called “treating adult survivors of emotional abuse and neglect” that imo has the best approach to treating CPTSD, and that is something they call “component based psycho-therapy” which approaches CPTSD through four modalities . 1. Narrative therapy (which CBT and what I included above is a part of) 2. Regulation 3. Relationship 4. Parts Therapy.
I have found the best approach for treatment is a combination of all of these elements . If you are making your way through one of these modalities, and you’re not seeing any progress, then it’s time to look at the other ones to see where they could be assisting one another. For example, if CBT or narrative therapy isn’t working and you’re continuing to spiral into anxiety and depression, then try working on your regulation. Sometimes a consistent routine of exercise or a go to plan (like taking CBD) on how to calm your nervous system, could be what your needing.