The drafts folder has saved more friendships than any apology ever did.

The sharpest version of what you want to say arrives about twenty minutes before you can think clearly. Sent, it becomes permanent and has to be walked back for months. Left unsent, it does the job it was actually for, which was getting the feeling out of your chest, and then it costs you nothing at all.

Write the whole message next time, unedited, and then leave it there. Read it again in the morning. Usually you keep two sentences of it, and those two turn out to be the ones you meant.