1. Realize that a great product has never been enough! How you treat people is very, very important.
2. Apologize to the client. Publicly. Why? You just humiliated him/her by posting the conversation. People value their privacy, even when they are seeking customer service. Now every client might think you are going to post everything online.
3. Either learn some CS skills, or hire someone to do it, or better yet, hire me to make you a simple CS script. It only costs a couple hundred bucks but will save you these types of embarrasments.
4. Erase that blog post, and replace it with a PG version. Specially the headline. You are trading credibility for traffic? Awful idea!
5. Publish a blog post stating your new customer service guidelines and feature it on the front page of the site. If this goes viral you are going to need to combat that.
6. Next time you feel like posting something like this just stop. Think! How would you feel if you were getting shitty customer service? Would you tell them to go fuck themselves? Of course you would! Always, always think about the other side of the coin.
Good luck. You will need it.