The way you are responding and analysing these 'graphic thoughts' is OCD. CBT to reduce these thoughts and elimnate the anxiety you feel in response, will not be the same and CBT for anxiety or depression. To deal with these thoughts, you need CBT geared towards OCD.
Some tips:
You need to see this for what it is, it is not depression, it is OCD, and needs to be dealt with accordingly. You are not mad, not sick, not a muderer, a psychopath a paedophile or anything else. If you are, then you wouldnt be worrying that you are nuts. You have OCD. So, when a though comes into your head this is what you must do:
1. Recognise the thought and relable as being OCD. Do not try to resist the thoughts, do not try to suppress it...this will make it worse. Instead, allow the thought to be in your head. It is just a thought and nothing else. So allow the horrible graphic image to be in you head, as you should not feel guilty for this.
2. Try not to attach anxiety to the thought. It can be in your mind, but so what? It is just a meangless thought produced by OCD which is playing upon subjects you dislike.
This is what you should do to begin with. How frequently do you have the thoughts? Do they impair your daily routine?
Do you do anything to stop the thoughts? For example, do you perform an action, either mentally or physcially? This is an important question