'Anger' is popularly considered one of the five stages of grief, first hypothesized by Elisabeth Kübler-Ross. The list has been expanded to six or seven since her early formulation.
Some of us find it useful to frame early sobriety as a mourning process, having separated from what for many became the most important part of their lives.
Google "stages of grief" to get a more comprehensive understanding of the grieving process.
“The world we see that seems so insane is the result of a belief system that is not working. To perceive the world differently, we must be willing to change our belief system, let the past slip away, expand our sense of now, and dissolve the fear in our minds.” W. James