Here is the problem: The prosecutor is an attorney who knows the rules of the law better than you do. If you don't ask your questions the right way, the prosecutor can object on a technical rule that will keep you from being able to have any witnesses answer your questions at all.
Even in Municipal Court where the rules are supposed to help people represent themselves, you need an attorney to guide you through the process. Most especially because a family violence case carries far more collateral consequences than a typical class C case.
An attorney can also remain emotionally neutral when your wife gets under your skin at the hearing. Imagine what the judge will assume about you if you even appear to get angry or frustrated at the process during your hearing. If your attorney is there representing you, there is someone on your side who can navigate the technical rules which can be major impediments to you getting a fair hearing or trial.
Also, as someone who works in the area, I can tell you that the Garland PD "policy" has caused great complication to many circumstances that sound quite similar to your own.
Call an attorney with experience in Garland and fight the accusations. Without expert help, you could end up in a spot where you don't end up with a fair look at what happened.
An assault conviction, even a Class C misdemeanor assault, can have long term consequences to your ability to find a job, rent an apartment or possess a firearm. This is a situation where you would be wise to hire a criminal defense lawyer. The judge will hold you to the standard of an attorney when you represent yourself. You have an uphill battle when you choose to represent yourself.
As a practical matter, the best way to defend against fabricated allegations of family violence is not to live with another person who you no longer trust. You must be willing to find a new place to live when your disagreements threaten to spin out of control.
Generally I recommend that the case not be tried to the judge but instead be tried to a jury. Judges tend to get a bit callous about cases and will follow the lead of the police officers findings more often than not. At least with a jury, you have people who do not listen to this stuff day in and day out and are generally more like you - your peers.
And, I would strongly urge you to get a lawyer to represent you. It is too difficult on this forum to coach you on how to get your evidence in, especially over what is currently an unknown objection.
And, it is not true that police must write a citation or arrest someone. Many times officers go out and find that they are there at a scene of an oral disagreement - which does not provide an opportunity for arrest or for a citation.