How can I print text messages from an iphone 5s?

Take a screenshot by pressing the Home and the sleep/wake button simultaneously. Theimage is stored in Photos. You can then forward the image to your email address by pressing the square with the up arrow on the bottom left of the image

What @Stinley suggested was the only way I could figure out to do it. It’s why I kept my old phone when I bought a new one. I didn’t care that I could turn it in for money.

I have a neat little H-P app that lets me print wirelessly to my
H-P printer. I’m sure other brands have the same kind of iPhone app and there may even be generic ones.

@Pachy There is no problem printing wireless from a 5S. The problem is there is no print function on the text screen. Are you saying the app creates the ability to print from the text screen?

You can take the screenshot and send it to yourself and print it that way, but I would actually give your phone to the police and have them take care of it as a better option because then you can avoid accusations of forging the messages and whatnot. They would look at her phone also, but it might be better if the police had your phone first.
I don’t know what state you live in or any of their police protocols, but my sister had an issue where she printed screenshots and gave them to the police, and they said they had to have access to the phone and they had to print it out/make copies. Might be different for you but just so you are aware.