A professor who supervises a sorority told me that she’s horrified by how many students keep screenshots of things their friends send them or put on social media, just in case they need it for retribution in the future.
If this describes you in any way, stop it.
If you feel the need to do this then you don’t trust the person. If you don’t trust the person, that person will already know, making it more likely you’ll need to use the screenshot. It’s a downward spiral.
Stop spiraling. Delete it.