People often make bad decisions when they are in a bad mood. They are overwhelmed by their emotions and their thoughts. They are so convinced that what they want to say is something that needs to be said. So they work themselves up and say how they really feel.
There's a couple problems with that. The first is that it isn't how they "really feel". They're just saying how they feel at the moment. The second problem is that the next day, they don't feel that way anymore, but what they said (or wrote) is still dangling out there, lingering in the minds of those who heard (or read) it.
When you communicate, your name is attached. Sure, people may use pseudonyms, but it can always be traced back to you. Be careful what you write. You may feel one way now, but you may change your mind later. However, once damage has been done, it's not so easy to recover.
Clear your head. Do something to calm down. Go for a run. Take a shower. Solve a puzzle. When you are not worked up and you are feeling more rational. Look at what you wanted to write, then see if you still think it's a good idea.