Hell no, I'd never sleep with a married woman, unless her husband says it's ok...
I had something very similar happen a while back... She was doing porn, worked in a BDSM dungeon and later I found out she was married, but she told me that she and her husband hadn't slept together in years and she was in a separate part of the house, I was still suspicious and asked her every question I could think of, she managed to answer pretty much everything...
But I was still suspicious because she wouldn't let me pick her up... Long story short, I found out from her sister in law who contacted me on social media that she was still very much married, not separated. So I dumped her immediately. I told her what I found out and I told her that was against my principles, I was just a shitty thing to do to someone else and frankly it was bullshit that she made me part of that...
So later he did file for divorce and her sister in law then contacted me again and showed me a post she made on facebook, (haha)... She said that I ruined her life and that I caused her divorce!! Now this is a woman who was in about 30 adult movies, had a fetlife profile with about 20 guys in it and was openly dating two another guys before me and one after me, before her divorce...
The whole thing was a mess, I deleted that account and never went back to that crap again... Anyway my point is that sometimes women have ways of turning things around and making them your fault; what if this one does that to you? Fight off the urges and find a different one, there are tons of good, single women out there...