Just as a friendly reminder: You will never look tough sending a threatening text message to someone. In fact, it’ll make you look like an insecure asshole. So don’t be that guy. Not only are you not going to be respected, you’ll likely lose your girlfriend over it.
Sure. Sticking up for your SO is something you’ve got to do at one point or another. But you should consider never going this route. If you genuinely have an issue with someone threatening your relationship, deal with it like an adult. Be there, face to face. You don’t want to end up in a screenshot debacle like this genius. Trust us, it’ll only go downhill from there. The internet will be there, napkin on their lap, ready to eat you alive.