I'm doing better but scared my bad stretch is coming back

I've had a few good weeks — actually getting sleep, eating regular meals, leaving the house without forcing it. But yesterday I had a rough day and my first thought was 'here it comes again.' I'm terrified of sliding back into that dark stretch. I know setbacks happen, but the fear itself is exhausting. I don't want to live waiting for the other shoe to drop. How do you sit with recovery without obsessing over relapse?