Your body is always sending you signals. When you want to communicate and make the decision to not to do it, it’s not because you are scared to speak up.
You are scared to feel the emotions that will pop up in your body while speaking up. Then a good or a bad communication are the probable results… Having to face them needs you to get out of where you are: stuck.
Speaking up frees, as long as it is done in a respectful way.