Q. "Are you absolutely sure that once we have cleaved the part of ourselves off that we refer to as “other” that we can then reclaim ourselves back to wholeness?"
A. I do not suggest cleaving off any part of yourself. I only suggest a shift in attention as awareness broadens and becomes subtler.
In the above diagram, M1 is already apparently self-cleaved, in the sense that M2 differentiates as M1 in relationship with O. So M1 senses difference and separation, which can be very useful.
O refers to an apparent object of perception–the other. Examples include my car, my thought, my feeling, my salary, my dreams, my brother, etc. When looking closely, we see that there is something of what we are in this perceived object. The only way we come into relationship with something is when there is some part of us–however subtle–that is a part of it.
This is not always recognized. So one technique that can be used is to shift attention from O to M1. Feel the contours of M1. Fully feel what it is like to be an individual. Feel the boundary that distinguishes "me" (or you) from "that". By attending to this, the sensitivity and subtlety of the mind increases and the M1 boundary loosens. Now M1 and O are not so different. This living recognition is the journey to M2. As M2, it is seen that M1 and O are undoubtedly, vividly essentially none other than M2, though as attention shifts they are appreciated as apparently different. This happens not by cleaving off any experience, but rather by efficiently using attention and awareness to include any and all experience.