How do you know how she behaved though? Other than what your husband tells you?
Are you asking me personally? This was fifteen years ago and I'm happily married to someone else now.
However while I appreciate you were seemingly innocent, please don't let that lead you to believe everyone is. The vast, vast majority of affair partners are well aware their object of affection is married.
In my case it was particularly cut and dried. I was given access to his email account where I was able to read the entire thing unfold in real time.
He was emailing normally, and she was flirting, trying to get personal, trying to get involved with him outside work. Eg: "Sam says you know about cars...I don't suppose you could pop down after work and look at mine as the brakes were sticking this morning"
On and on, for months. Popping into his office with little gifts. Hitting on him at work events. Eventually befriending him and providing him with emotional support when his Mum died.
I then was able to read after the sex, him saying how much he regretted it and could they please just be close friends. Then late night messages begging him to just see her because she "needed him", laced with threats to expose him.
So in my case I know how she behaved because I saw it. I also endured her on my doorstep, at my workplace, calling my home and harassing my children at school because she was a complete cunt of a human who couldn't accept when he said he wanted nothing to do with her.
We didn't end up divorced because he was unfaithful. We ended up divorced because she wouldn't leave our family in peace an eventually he became extremely ill and had to give up his job and so on.
I realise that's a particularly bad cases, but time and time again I see these characteristics in OW. A lack of empathy. Entitlement. Complete inability to behave with decency.
Hence I completely despair at the way a lot of these threads try and make out women have no right to blame or be angry.
Let them blame if they feel they've been wronged.