This has happened to me in the past. You can try writing about your writing and wondering why you’re gravitating back to the topic, and why you’re feeling the emotions you’re feeling. Write about the fact that you’re getting worried and brainstorm reasons why this may be and what you can and can’t do about it. If it’s too painful, you can try stepping away from that and writing about something else entirely. Like follow a week’s or more worth of prompts. So you are still writing and expressing but intentionally away from that issue. If it is all too painful, take a break. Many diarists take breaks when things in life become too much. Most come back because writing is how they cope.
I am sorry you’re experiencing negative emotions. I wouldn’t worry about that, per se, it’s ok to feel those things. I hope you can write your way through it