You'd be better off not stalking the wife's SM, but ... you're only human.
So see those posts for what they are - desperation.
He's not Her Love, he's a cheating arsehole who the wife is clinging onto by the skin of her teeth, thinking she's just won the Pick-Me Dance.
www.chumplady.com/2012/04/the-humiliating-dance-of-pick-me/
If you haven't come across the brilliant Chump Lady yet, follow the link above, then browse the archives - you NEED her wisdom, hard-bitten experience, & above all snark.
This man is on a strict regime at home & his wife knows she can't trust him to have so much as an unsupervised phone call with you:
If you would like to discuss any of this in a phone call we can arrange to do that, but only on the understanding that firstly, I will not change my decision, and secondly, X (my wife) will be present during any discussion that takes place.
She will never trust him again, she will spend every evening he's 'working late' wondering what he's up to, if she's smart she's got all the humiliating joy of an STD test, & her confidence will be at rock bottom.
She hasn't won any prizes here. So don't wind yourself up about what she's posting on SM, she's as devastated as you are, & kidding herself that 'saving' her marriage to a cheat is something to celebrate.
None of us can advise you what to do about your pregnancy.
Just make sure you base your decision on what YOU want & what will make YOUR life better for the next 20 years.
I'm so sorry this man lied to you. You mentioned his lawyer-cold wording in his letter & how you dread that this will be the cold persona he presents to you at work now, saying that it's a complete turnaround from how he used to be with you. Bear in mind that the cold persona is the real him. The other guy, the one who was warm etc etc etc to you ... that was just a style he adopted to get what he wanted from you. It's a construct, it wasn't real. So don't you go pining for it. You are better off without this shit (& so would his wife be, but she, like you, has her own long term decisions to make). 