Will my previous charge affect whether I am convicted and/or serve jail time?

A class C misdemeanor offense in your criminal history is not going to affect whether you are convicted on this case. A conviction for more serious offenses (Class B and higher) can affect your current charge because it can enhance the punishment for the current offense.  However, not true for your situation. You can review how enhancements work under the TX penal code here: https://statutes.capitol.texas.gov/docs/pe/htm/pe.12.htm Around half of the complainants ("victims") of assault family violence recant their report to law enforcement. Due to this fact, the prosecutors don't automatically dismiss cases just because the victim changes their story.There are situations where an affidavit of non-prosecution may be helpful, I just would caution against regarding it as a silver bullet for the defense.