I personally try not to read too much into what Erin must be like based on the written accounts that we hear. Based on only a selective number of facts, I don't think we can get enough information to state what she is really like. The reality is that everybody lies, and many people under extreme pressure act in a way that is not normal. She has been coming across as very defensive in the last few days, but I don't think that is unusual.
That said, there have been little indications that remind me of one of my exes, and I have wondered whether she could display similar traits. One thing that caught my eye, was the idea that her and Simon were very regularly on and off - very little has specifically been mentioned why this is, but that she seemed to take it very badly when he wrote down separated. My ex would routinely finish us for months at a time even, but when I finally said I'd had enough she was begging me not to leave. I realised later it was a form of control and manipulation.
The other trait is that my ex rarely had a good word to say about people, and as such you developed a very warped view of what people were like initially. It took me many years to realise that maybe her ex-boyfriends weren't all the worst people who had ever lived. I often wonder what impression her subsequent partners have of me, as I'm sure I was painted in the worst of terms. Whereas I have only had 1 partner since who I have been happily married to for well over a decade, she has unsurprisingly had a number of failed partners and never settled, none of which will be her fault.
I could be miles off the mark, but it does make me wonder, how bad it Simon really? Her claims that he was controlling could be vastly exaggerated and she could in-fact be the problem. My partner once called it emotional abuse when I refused to take part in a full-blown argument, insisting we calmed down first. Maybe Erin is somebody who throws around terms that are completely unrelated to reality.