Q: Regarding the (Texas Penal Code § 46.04. Unlawful Possession of Firearm)

A: The quoted text isn't the law. Rather, it is someone's interpretation of the law, and it is incomplete because the law also includes people who are parents of the same child regardless of marriage or dating history.

In addition to Texas law, you need to be 100% certain that you are in the clear for federal law. The feds have a LIFETIME firearm ban for people convicted of any felony or a misdemeanor crime of domestic violence. Their definition of "domestic violence" is not fully congruent with the Texas definition of Family Violence and can be found in 18 U.S. Code § 921(a)(33).

The federal law includes offenses involving "the use or attempted use of physical force, or the threatened use of a deadly weapon." This means offenses involving attempted force that somehow fails and some types of threats can disqualify you under federal law but not the Texas law. That said, a threat with a deadly weapon could be charged as a felony in Texas, and any felony triggers the federal firearm ban.

As for the victim, the federal definition applies to a "current or former spouse, parent, or guardian of the victim, by a person with whom the victim shares a child in common, by a person who is cohabiting with or has cohabited with the victim as a spouse, parent, or guardian, or by a person similarly situated to a spouse, parent, or guardian of the victim." A person similarly situated to a spouse could be a common-law spouse or live-in romantic partner, a person similarly situated to a parent or guardian is an adult that has assumed control or responsibility for a minor.

As for what needs to be done, you are on the right track. Examine 46.04 of the Penal Code, the definitions it references in chapter 71 of the Texas Family Code, and 18 U.S. Code § 921(a)(33) for the federal definition... the actual federal ban is in 18 USC § 922 but the definition in 921 is the key.