Keep the chat safe. Wanting to ping your work friend about how much you dislike your job can cause you harm. Pinging a group chat by accident or DMing the wrong person could have serious implications. A good rule of thumb: Never say something on chat or email you wouldn't want your team to hear.
Choose wisely who you should vent to. It is better to chat with someone you trust than with a new intern who may not know what to do with the information.
Write it down until you feel some of that tension ease up. It may even help you to think more clearly about the issues you're facing.
Take a walk. A brief stroll can help distract you. It can also lower your blood pressure and boost your mood. You can also share your troubles with a confidante in a way that doesn't compromise the work environment.