If your spouse filed for divorce, the court expects you to respond. If you don't, not only will your spouse get the divorce he's after, but the court will likely give him everything he asked for in his divorce complaint as well. Responding involves filing an answer telling the court which parts of your spouse's complaint you agree with and which you don't agree with. If you want more from your spouse than just a divorce, such as spousal support or custody, you can ask the court for these things by also filing a counterclaim.
http://legalbeagle.com/7663528-counterclaim-divorce.html

A counterclaim may accompany an answer to a complaint. In a divorce action, a counterclaim alleges the defendant’s (or respondent’s) answer to the plaintiff (or petitioner), as if the defendant were the party asking for the divorce. In some cases, a counterclaim may allege adultery.
Normally, defendants must answer the complaint and file a counterclaim within a period of time, usually less than one month. This amount of time is clearly stated on the summons which is served on the defendant with a copy of the complaint. The plaintiff then may file an answer to the counterclaim. The title of petition is often used in some states rather than complaint.
In uncontested divorces, there is not a counterclaim, but rather some form of acknowledgment by the defendant that he or she agrees with what is presented in the complaint.
Failure to file a counterclaim (response or answer) to a complaint will result in a default judgment or decree.
http://www.divorcesource.com/ds/encyclopedia/counterclaim-19...

--------------------------------------------------
Note added at 21 mins (2017-02-01 19:19:53 GMT)
--------------------------------------------------

Do-It-Yourself Answer and Counterclaim for Divorce
http://michiganlegalhelp.org/self-help-tools/family/do-it-yo...

ANSWER & COUNTERCLAIM FOR DIVORCE WITH MINOR CHILDREN
http://www.chattahoocheefamilylawcenter.org/forms/Divorce-Ch...