She had a bad thing happen to her when she was young is she going to let it ruin her life? And yours? It's genuinely about time she got the f&ck over it and it's about time you led the way.
Responding only to the suggested tone, I can tell you what has NOT worked, and that is getting angry and "laying down the law", and "telling it like it is". She does not respond well to the motivation that she "better do this and that or my husband is going to be angry". Telling her it's about time she get the f**k over this thing does NOT work at all. If it did, I wouldn't be here posting!
Well, no, that wouldn't work: it's childish and bullying and treats your W as though she were your inferior.