I think I know what you mean! I get dissociation when my thoughts become too overbearing. The disconnecting of yourself from your identity (the "I") is particularly scary for me. I'm not sure I know what could make it go away entirely since everyone is different, but as for short term relief, focus on distracting or taking care of yourself.The most helpful thing for me is having someone you can message or call to ground yourself back to reality. Put your focus on something, like tv or a computer game. My own therapist even recommends a mantra sort of thing, like saying "I am (your name), my name is (Y/N)". Sorry for the long response, its an issue close to me!