Lex, everybody comes here and reads each others' posts and say, "Hey, that's just like my wife/husband!" We're all astounded by how spouses seem to follow a script. But the specifics of your situation are so similar to mine, it's eerie. I am not going to point out those specifics because of privacy concerns but if I did, you would be puzzled. How could this be?
Anyhow, here are some things to consider. Your W's childhood, including all those boyfriends and abortions, and her (seemingly) unfulfilling relationship with her parents, could have been deeply emotionally damaging to her, and could be strongly affecting her even now as an adult. I think your wife may suffer from "borderline personality disorder" (BPD). There are many websites and books on this (I prefer books because the quality of information on the Internet isn't very good.) Don't be misled by the unfortunate name of this condition. And I'm not saying your wife neatly fits into this. First, BPD is difficult to diagnose and must be done by a specialist. Second, as with many psychological conditions, a person doesn't neatly fit into a category; people are complicated. Whatever you do, don't bring up BPD with your wife. It is counter-productive to tell her directly about it (so say the professionals.)
I recommend that you talk to a mental health professional who is familiar with BPD, and get some input. They'll see spouses of people suffering from BPD. Even if your wive does not have BPD, it's really helpful to see a counselor about your failing marriage. If your wife does suffer from BPD, I believe it would explain a lot about her initial interest in rape fantasies and the later accusation of rape against you, as well as her delusion about having a relationship with the celebrity.
Man, I wish I could give you a phone call and talk.
p.s. Is there any parallel between her behavior within your marriage and her mother's (or father's) behavior?
Me: 50, MLC/WW 45 Young kids Nov 2015: BD1 Apr 2016: BD2 Jan 2017: W filed Feb 2017: D final