Feeling of unbecoming & losing I-hood
Don't try to conceptualize what is happening. Simply stay aware and let-go.

If you have reached to that point, have courage. Obviously you will be afraid, it is the death of ego, a conscious death.

Some wisdom from the Buddha,

There are only two mistakes a man can make on the path of Nibbana, one is never starting at all and second is not walking till the end.


Again as the Buddha said,

Charaiveti Charaiveti.



Edit: The third point is a fake buddha quote. My bad.
The fourth one is apperently what the Buddha said at the end of every discourse. Meaning, ' go-on go-on'. This has been said by some,  but there is not strong evidential cititation. But feels like right.