@K14N what you describe sounds familiar.
Shinzeng Young calls it "the evil twin of enlightenment".
You experience the same oneness/void/goodconsciousness as people experience it in enlightenment BUT with a sense of total disconnectedness.
oneness + feeling of total connectedness (love) = enlightenment
oneness + feeling of total disconnection (absence of love) = evil twin of enlightenment, Derealisation, ego-dissolution
The border between the self and the environment dissolves and you experience oneness but without a connection to "someone" or to yourself.
A connection is then needed. An authentic deep connection with a "person" or with yourself. It is easier to start with a connection to another person. Even when you feel all is one, you see other people. And for the deep connection it doesn't matter if you see the other person as seperate or as a part of your own consciousness. Important is the authentic, benevolent and understanding relationship. It needs someone you trust and you feel safe. Someone with whom you can share your fears without the fear of rejection. Perhaps you can find a therapist, a nurs, a doctor... someone who doesn't leave when the massive fear arises an is still open and can acompany you.
I know, it is hard, and it's quite difficult to find someone in that situation.
I wish you all the best