How do you respond to a divorce petition without a lawyer?
It is like asking how to cure a serious medical problem without a doctor. If you have legal acumen and knowledge and do not want to spend too much on lawyers, higher a mediocre one that could charge as per your convenience and work along to contest your case. Doing it entirely without a lawyer is not advisable, in my humble opinion. Court may allow you to do the same but it is not a movie scene and specially difficult to do in a trial court where you need to be acquainted with procedure and other aspects of evidence and substantive law apart from landmark judgments required to prove your point.