What should probably be social media rule #1
1. In the height of passion, type your comment into a text editor. e.g. Notepad
2. Wait five minutes.
3. Read.
4. Consider your audience and possible consequences for you or someone else.
5. Read again - edit if necessary.
6. Would you like this on the front page of the New York Times?
7. Choose between copy-paste to online or the delete key.
--- PS, personally learned the hard way... B^)