It sounds like you're feeling a bit stressed about your upcoming interview, and we totally understand why. Interviews can be nerve-wracking, especially when you're not sure how to answer certain questions.
When it comes to explaining why you left your previous job, it's all about framing it in a positive light. You want to focus on the reasons why you're looking for a new opportunity, rather than dwelling on the negative aspects of your old job. For example, you could say something like "I'm looking for a new challenge" or "I'm hoping to find a position with a lighter workload." By phrasing it this way, you're showing that you're proactive and motivated to find a new opportunity that is a better fit for you.