Is it illegal to text cuss words?

I doubt you will find a website that specifically addresses this issue since it is pretty much common sense that the government cannot regulate the conversations between two adults. There is no law against me telling my wife she is a worthless cow and sleeping with my secretary (not that I would do either of these) but of course they would be relevant in a divorce case. Now if you had a restraining order against your husband and/or he was also making threats, she might be onto something.