Who is Mary Smythe ne Parnell (Octopussy) from Octopussy and what is their importance?

Mary Smythe is the ex-girlfriend from wartime MOB headquarters whom Major Smythe married when he resigned from the Royal Marines. From a solid middle-class family, she has no idea of the ramifications of the currency laws or the origin of Major Smythe's gold. When she is unable to prevent his heavy drinking, she becomes an addict to sleeping pills and takes an overdose in a fit of anger after a drunken row. The overdose is lethal.