The book was never written by al-Waqidi. Hundreds of years after him, someone claimed that this is his work and from then on people began attributing it to him. The book quotes authorities who were born after Waqidi, it even quotes Waqidi himself! It contains many false stories like the ones of Khawlah etc. Here is a link to an Arabic pdf discussing this false attribution. In short, don't touch the book.