Trailrunner I understand the feeling of having "something" move in on you like a physical sensation or an emotion or a knowledge and feeling like if you leaned into it you would fall into a black hole. I have experienced exactly that kind of feeling with somatic memories and other parts of me. There are times when I am me but aware of something else (like you've described) and I have a choice to take flight from it (purposeful escape it numb it avoid it etc) or I can turn my attention to it and ... Well. Sometimes that ends up with coconscious sharing and sometimes it ends up with horrible flashbacks.
It can be a real struggle to understand where these snippets of emotion/sensation/knowing come from or what they relate to.