Legal Question in Family Law in Texas

That would fmdepend on exactly what you mean by "never legally married". Do you mean that you really were never married at all (in which case you should not have been filing taxes together, obviously)? Or do you mean you were at least potentially common-law married (considered yourselves to be husband and wife, held yourselves out as husband and wife, and lived together during the time of the first two things)? If you were common-law married, then yes, you do need to get a divorce, kids and assets or not. If you really, truly were not married at all, and were lying about your marital status to save on your taxes somehow, then you may not need a divorce, but I'd sure find a good tax attorney--the IRS does catch these things every so often.

If you filed taxes with a married status, that could be used as evidence that you had a common law marriage. Hence if you wanted to get married again, you might think about ending the common law marriage. This would require a suit to prove the marriage as well as a suit for divorce to end it. If you did not end the common law marriage first, you'd have a potential bigamy charge lurking out there.