There's a great article about journaling, heBusiness Insider. It not only lets you know (again) how journaling can be helpful, it has a writing prompt to use and explains why it is so helpful. (As good as an antidepressant without the side effects!) One of the things it says is to really write about what is bothering you and why this helps so much ...
"The foremost reason is disclosure. Psychologists are basically in agreement that avoiding or inhibiting unpleasant emotions or suppressing your thoughts makes makes your body tense, your mood negative, and your cognition impaired. But if you access, express, and process those blocked-up emotions, you'll feel better, in all of the ways. For the same reason that talking about your breakup with your best friend makes you feel better, journaling about getting fired lets you process it."
So dig in, start journaling. Write the bad stuff out and then if you don't want to keep the notebook around, throw it away or burn it. Get that stuff out.
You will feel better.