Legal Question in Wills and Trusts in Texas

Whether or not the will is "valid" depends on factors that you haven't told us about. Was someone holding a gun to his head when he signed it? Was he insane when he signed it?

He can only will property to someone (making a will is, basically, giving awayone's property) if he owns that property. If I make a will that leaves my neighbor's house to my children, it isn't effective.

Other than that, I can leave my property (give it away) to anybody I want to.

Mr. Dunn points out a couple of the many reasons why a Will might be challenged, and I'd encourage you to visit with an attorney to further explore the rights of the parties here (mistress, wife and children). Leaving property to someone who is neither spouse nor child is not by itself a legal basis for challenging a Will. As Mr. Dunn points out, a husband could leave his spouse and/or children everything or nothing. But, the husband can only leave that part of the property that he actually owns, and in all likelihood, your case involves some community property he shared with his spouse. Thus, even if the Will is valid, it's almost certain to create some very awkward ownership issues that will very likely take some lawyers to work through.