The reason a woman will test you, as a man, is to see if you are fearful.
Based on this thread, your reaction, the assumption, safe to say she see's you as fearful, or at minimum, you see yourself as fearful and that is going to show.
Even before the question, "Did she cheat?" Even before the wonder of where she was... You numb the fear before any of that. She can yell and scream at you, then apologize for doing so later, but only if you do not engage with her emotions.
As a man, you MUST treat all tests a woman gives you, like a child is trying to get your attention, you ignore.
Whether she did cheat or not, who cares, you have a DNA test if it really comes down to it, but point is you can never show that fear of her walking away or cheating, if anything, you sooner be ready to walk away than her... Maintaing respect in this way, yeah in the short term its not going to be good for you, but later on when you see these women, they will speak well about you, because you left them, thus, they see you as high value.
Always leave a woman on good terms... A cosign of a woman, in the eyes of another woman, for a man, is invaluable.