My advice is to hold your investment for 2 more years. Rule number one is investing is buy low and sell high. What you don't want to do is to sell at a 2 year low.
As others have suggested, this is a great time to double down and buy more- buy near the low. The stock will be over 13.5 sometime in the next 2 years. There is very good probability, the price will go over 20 sometime in the next 2 years. This is a terrific company with excellent management. In time, the value will be fully realized.
You should ask, "why did I buy this then?" If your reasons have not changed, then you should not sell, but instead buy more at 1/2 price and sell when it gets to your initial price or until something with the company changes for the worst that would prompt getting out.