My knowlege is based on things I know about her husband (I've known him 20 years), things I have heard, and things I have observed (sometimes I run into him and his girlfriend through work functions). Some are actions I've seen, but yes, some things described to me by her, or various others...
By the way you wrote "I don't think you can safely take the word of a WAS, even if they're your best friend or bff."
I'd like to add to that I don't think you can't "safely" or accurately take the word of a WAS or LBS even if they are your BFF. There is always more to every story. Things we don't know, and things twisted to manipulate the listeners feelings one way or another.
One thing I can honestly say about this friend, she has never maligned or spoke badly about her XH to justify her actions. She typically doesn't talk about her XH or say anything bad about him. What I see in him is tremendous anger and hatred. What I see in her is sadness. And yes, she caused it...
Although... interestingly. I'll throw this one in...
About 13 years ago this woman's H had an affair and was going to D her for OW. I know about this because we were friends at the time. Young married couples with babies... and my H had just had is first A so we were able to commiserate and support each other in repairing our marriages. I had always thought she was more successfull at working through it and getting over it. I was the nut...
Now Blues, she could have used that for an excuse for her A and wanting a D. But she didn't. She just said she was unhappy and wanted something different. She even said he was a decent guy, just not what she wanted...
There is no arriving, ever. It is all a continual becoming.