I'm beyond distressed

I have a technical interview tomorrow morning for a job after 18 months and I feel like I'm going to fail. I have no idea why though because I've been damn good at my jobs for 20 years. I just have a 6 month old that I watch 5 days a week, work a fast food job the other 2 days, a spouse that is recovering from cancer, a disease that the chemo had on him, and now an appendicitis. I NEED a job, I am running through money faster than I can make it. I'm worried that all of these pressures put more stress on me which translates somehow to my interviews.