Stress is a reasonable response to a range of situations. It’s OK if you’re feeling angry, depressed, or frustrated, but you need deal with it.
You may benefit from some breathing room. Ask for a medical day off. You could even get a note from your doctor. Don’t do chores. Get away, at least mentally. Binge watch something, go see friends, and so on.
Ask for some support from your manager, HR, your doctor, your partner, or family members. If someone you trust at work reaches out to you on their own, they probably have your interests at heart. Otherwise, be careful about sharing with fellow workers — you never know who might try and take advantage. This goes double for posting about it on social media.
Your stressed-out emotions are not necessarily the business of the people around you at the office. Remain professional even in the face of the most upsetting events, and get yourself somewhere else where you can let it out without negative consequences.
When performance review time comes around, professionally and diplomatically describe the issue you’re having. (Don’t be personally critical of anyone.) You’ll be able to point back at your review to show that you did what you could to resolve things.
Consult your employee handbook and see if there’s anything there you can use to get help with a problematic coworker.
If you’re in a union workplace, you may be able to get help from the union in resolving the issue or at least help in mediating a way toward a solution. If you’re not, the Fair Work Commission has lots of good information on resolving workplace conflicts.
Stress is real, and it doesn’t mean there’s anything wrong with you. But given how damaging it can be, you’re better off dealing with it while you still can, before it swallows you whole.