Texas dicorce based on adultery?

So my father is going through a dovorce with a woman that is only after his money. Shes trying to say he commited adultry but he never has. His ex wife visited him for a few days but nothing happend. The thing is she has no proof other than a beliefe and she has no proof of his ex (my biological mom) over at his house. Although mydads ex sister in law lives nextdoor to him.. if she signs a deposiion could it be used for circumstantial evidence even though there are past transgretions that are possible. Nothing did happen shes been after his money sonce the start... she even forced him to kick my wife and us out because she didnt like me...