I agree, while it would have been more open, honest, forthcoming to mention his marital status from the beginning, as long as you were simply FB "friends" there was really no harm, no foul.
All of that changed however, the minute you both decided to meet in real life. At that time, IMO, you both needed, if there was any chance for a real/honest/open relationship to develop, to divulge anything that would impede that chance. IMO, When things turned towards the intimate, not revealing his marital status beforehand so you could make an informed choice, made him a manipulative liar.
How do/would you know that he actually talked with his wife? Why couldn't/wouldn't he just tell you that she was OK with him being involved with someone else since they are married, "in name only"?
Case in point- my ex and I are still legally married but legally separated and have been for 10+ years. At one point he got engaged to someone else. She called me on more than one occasion. Quite frankly because he was lying to her and using me as the reason why he couldn't do what he promised her.
The last time she called was to ask me why I would not sign the divorce papers. I had in the past told her the ex lied as easily as he breathed and if she believed him after learning that fact, it was on her.
Truth be told there were no divorce papers to sign. We had it written into our separation agreement that if/when either party wanted to finalize the divorce all we had to give the other party a 90 day written notice of intent, then file papers with the court. Once the papers were signed by the judge the divorce would be finalized.
The ex had no intention of marrying anyone and being married to me and having me as the excuse made it easy for him to get what he wanted with ease.
And just so you know, my ex gave his fiancee my number when she asked and made sure he had a story to tell me every time she was going to contact me. She finally stopped contacting me after the signing call and I told her to stop harassing me or I would take legal action. They broke up soon after that.
So, I cant help but wonder if he will lie to you and tell you she knows, is fine with everything, just so "he gets what he wants with ease."
Have you given any thought to the questions I posed?