After an hour, you’ll hopefully feel a little calmer. Now you can go back online, if you feel up to it, maybe even with a friend or family member in the room with you. The idea at this stage is to get a proper feel for the situation before contacting the person who is cyberbullying you.
Using calm, neutral language, try to work out the situation with the person without letting them get to you. They might not even realise that you interpreted their actions as cyberbullying, so a calm conversation is a good place to start.