Firstly, any woman regardless of mental condition could do what Jack the Ripper did. Certain parts would be harder, but not impossible. Secondly, Multiple Personality Disorder doesn't exist. Disassociative Identity Disorder is the name of what you are thinking of, and it is not quite the same. It's also incredibly rare, if it exists at all, and most people thought to have DID are actually psychotic. However DID has a lot to do with social norms, the victims having experienced abuse or incidents well outside societies definition of normal. Because social norm were different in Victorian England, and impoverished children especially had no expectation of being treated in a certain way, it is highly unlikely the disease ever even presented before the the early 20th century.