I have nothing insightful to add to the comments of your DB friends who have already replied.
If believing that reconciliation may not happen is not possible,maybe tell yourself that is is a five year process after which she will come back. Now what are you going to do with the next four years?
A few years back I often had similar dark thoughts.It is not a good place to be. Everyone has down days. Pick yourself back up and treat yourself to a small pleasure today.
Best wishes
R 25 years M 14 years S11 & S13 Working on it alone since Oct 2014 M in trouble a lot earlier (~2 years) Feb 2016. 1st R chat in a yr. Next R chat Aug'17 Still together