I'm not sure if you've tried psychedelics. Psychedelics have very different effects on people, but I was very lucky; on me they produced exactly the effect you described - reducing my mental processes to far more granular levels. I did psychedelics enough that now this type of 'unfusing' process feels somewhere between 'default' to 'always present but sleeping' to me. I feel rendered mute when trying to talk about this, because this topic triggers a strong inability in myself to remain fused with the thoughts I am trying to handle. It also makes me cry, which makes discussions awkward.
I've spent a lot of time in rationalist communities trying (and failing) to talk about this topic (cause of the crying). Reading stuff like this makes me feel a lot of emotions and gives me a desire to be around you and Valentine and the others who are saying similar things.
-edit: did not know about the pm feature