I think we need some optimism here. That nest may be empty but it is also quiet, can be cleaned out and rearranged and demands much less of your time. This is good. You are not primarily someone's mom anymore. There is discomfort with this at first, but now you can go back to you being you. That nest is empty so you can perch on the rim, not to look back, but to shake out your wings and leap off the edge. Reinvent, rearrange, shake things up. Start a new adventure for this phase of your life.
A wise lady (me) made up a new saying for this time of life: "An empty nest does not mean your life is over. It means it is time for you, too, to fly!" Leave the nest behind -- there's so much waiting for those who fly!