None of us likes to hear of anyone making a loss, theres enough money being pumped in each month for us all to have a piece of the pie.
As to whether to close a short on the dax? Look at the last 5 years on a daily chart that says it all. There would need to be a reason for the Dax to turn around now and at the moment (short of all out war with Russia) things are just getting better and better in Germany. Euro QE is only just beginning, all time highs on Dax, FTSE, Dow. The longer you stay in that short the more money your going to lose.
Walk away, have a think about a different strategy, and come back when youve gotten over the anger and accepted the loss. At the moment your still in denial, you need to move on.