He's going home to his wife and shagging her having stuck his dick repeatedly in his work colleague (very vulnerable work colleague, out of an abusive marriage with little apparent other relationship experience), aw yeah, he's a lovely guy.
Now he needs therapy to answer why he proceeded with every action that led to him repeatedly shagging his work colleague with a wife and kids at home .... He doesn't need therapy, he just needs to face up to what he is ... But he won't. The nice guy act is self delusion as well.as convincing to others; probably why he's so convincing.
While I appreciate it's tough reading for you OP, can you not see this? Genuinely?
That it's vanishingly unlikely he is the exception to the rule and is in fact someone who is having his cake and eating it too because he can and is getting away with it.
If she found out, he would tell her you pursued him, you wouldn't take no for an answer, you wouldn't cut contact, you didn't mean anything, you were just an escape, he would beg her not to leave him. Can't you picture that and how humiliating a position he's got you in, to make you cut all contact not related directly and solely to your work?