You can always respond to a text with an email. Depending on your phone, you may be able to copy the contents of the text and put it in an email. I know that you can do this with an iPhone. There also may be applications out there that allow you to download text messages to your computer.
This assumes it is a smart phone: Nit everyone has one.
I am not aware of any way to "download " text messages. Not every phone has "apps--ONLY Android and Iphones do.
I still recommend NOT using text if you need to track content.
i know i can send text messages to my email so i covered there but the phone calls are a concern because shes made statements to me that lead me to believe shes willing to conjure up things to try to mess with me