Is the review truthful?
Sometimes the truth hurts and while the review might feel mean spirited, maybe there is a bit of truth in the review that needs to be addressed. Your friends are most likely not going to tell you if your food has room for improvement or if your store looks sloppy. Maybe this negative review is the wake up call you needed. It might be a good idea to start consulting with people outside your immediate circle of friends. Or maybe have friends go in as secret shoppers and report on the customer service. Be willing to pay people to give you honest feedback.