I agreed to nest at the beginning of our separation because H sold it as a trial separation and I was desperate to not believe that he really wanted to leave.
It was brutal and I wholeheartedly do not recommend it. H used it as an opportunity to point out all my flaws and justify his departure 'the house was messy when you left' (it wasn't), 'you left me with no food' (I didn't) 'you purposely left my dirty laundry and didn't do it with the rest of the kids' clothes' (not true, I just didn't get to laundry those two days). Transitions were awful, and the fact that I had to see him and his shark eyes every few days nearly killed me. Peace became more attainable when he actually moved out for real and I was able to claim my space, get into more of a rhythm and start to heal.
And the kids were mightily confused. It was like pulling an old, stuck bandaid off reeeeaalllly slowly. Because H wasn't willing to tell the kids or me the truth (he wanted out and wanted a D), they didn't know up from down. Nor did I.
Nesting is for people who either are amicably separating and have a clear, defined direction (and are both on the same page with themselves and the kids) or it is for cake-eating walkaways and waywards who are confused about what they really want. H had 2 or 3 reconciliation attempts during our nesting phase when he told the children we were never going to get divorced, he loved me more than the earth and sky etc, etc (vomit) etc.