On page 13 the Sentinel tells Creon, "you heart-ache were the doe's, your ear-ache mine."What important lesson is buried in the Sentinel's comment? Antigone by Sophocles
There are few things to note before answering your question. You should refer to the quotes of a play by line numbers if you have them (and with Sophocles you will), since the text can be found in many different types of editions, and page number will not always be a consistent reference point. You should also be aware that this play was originally written in Greek, and that there are many different translations of it. So, when you are asking for help regarding a specific quote, it is useful to know which translation you are working with.
That said, I have found the quote you are referring to at line 319 in my translation by Elizabeth Wyckoff. The line you quote above is given in my text as:
The doer hurts your mind. I hurt your ears.
The lesson for Creon that is implied in this line is one that reflects Creon's tragic flaw -- his unbending adherence to the strict and unyielding laws he has set up in Thebes. Someone, the Guard reports in this scene, disobeyed his strict law and buried a body he had ordered to be left unburied.
So, it is Creon's mind or his pride of ruler-ship (or as the line is quoted from your text, his heart) that is wounded by this action. The lesson that the Guard is potentially teaching Creon is that, this report that he gives is really only words that he is listening to, not necessarily the huge and earth-shattering event that Creon will make it out to be. This insistence on correcting the wrong (the burying) and punishing the perpetrator (Antigone) will bring Creon's rule down around his ears.