This is important, and if you've been an auditor for a while, then you've definitely been overloaded at some point. This is a good time explain the situation and how you resolved it. Knowing that even if you stepped back and had to ask for help is the right answer.
You should never fabricate something, so if you don't have experience being overloaded with work in the professional world, turn to the academic world. Most people have been overloaded at some point in their lives.
"When I was an analyst working on a User Access Audit, I was so overloaded with work I was reviewing 11 systems that all came in at the same time. I was working from five in the morning until eight at night and I just muscled through it. I was able to get everything done quickly and accurately, but I was stressed out for a few days. I felt so accomplished when it was done that I knew this was the career for me."
"When I was in college, I was on my own. I went to school and lived in an apartment off campus. I worked three jobs to maintain my apartment and my courses without going into debt and I played basketball for the school. I was so busy that I had a reminder set on my phone every time I needed to leave one place to get to another. I once left a game and went straight to work at a restaurant where I was a waiter before I went to the nightclub where I was a bouncer. I would generally get up at 4 am to get to the coffee shop where I worked in the mornings before classes. I was able to get through school debt free and pass all my classes to get to were I am today. Yes, I was overloaded, but I can handle it."
"I once was managing four different teams, and each team had at least five projects they were handling at a time. I had various team meetings to discuss the projects and get updates while I handled the finishing touches and was the control owner for many of the controls being tested. My teams were so overloaded we could hardly keep up, but thanks to the help of my dedicated employees, we were able to maintain the pace until I could get a bigger budget and hire more people to help."