I can absolutely understand what you experienced and, like you, have no simple words to describe it. Here’s an attempt. We are the universe, however we are biologically programmed to view ourselves as separate, which in important ways we are. Unity and separation are just one of the infinite dualisms possible. The first universal experience was perceiving that truth. The second, more chaotic, experience was transcending the whole/separate duality and perceiving the flux, push/pull of all of the infinite dualities that exist as logical possibilities inherent in the very definition/nature of the infinite source of being. It’s quite jarring for our minds to tap into that. I had what others call “kundalini syndrome” after doing so myself. Now I play with the flux, not trying to control but just experiencing and experimenting. I’ll end this already too long response with this; “The Tao that can be named is not the eternal Tao”.