Regret fades in a week. The screenshot is forever and has perfect memory.

The feeling that follows a bad message fades on a normal human schedule, and the record does not. That mismatch is what catches people out, because you weigh the risk against how bad you expect to feel rather than against how long the evidence lasts. Your memory is merciful; the archive is not.

Add a gap between writing and sending when you are angry or hurt. Draft it, leave it unsent, and look again in the morning when the feeling has moved and the words have not.