How should Gerald tell his story to the Inspector?

I'm sorry, I'm not quite sure I understand your question. Gerald should answer the Inspector's questions with honesty. Unfortuately, he tries to avoid the questions, which immediately signal something he doesn't wish to share..... he seems to be embarrassed and most uncomfortable when asked to stay. We soon learn that he had a relationship with Daisy (Eva) while he was involved with Sheila..... that she was his mistress.