I think the best way is to extract them from your chat. Export your chat history with your wife (or husband) and then email it to yourself. Once there, you can paste neatly into a word document. The export will capture the full timestamp, name of the message sender, and the message itself. It's a clean way to present the information.
The alternative is to literally take screenshots of the texts, but that is a very tedious task and sometimes it's often nearly impossible to scroll all the way up to the message(s) that you want to screenshot.
Best way is to use the export chat (text) format.