(((twodoves))) "Thinking the worst" is actually a pretty wise approach, early in the game; while it's not unheard-of, few WSs tell the whole truth right away. Many never do.
I am so, so sorry you've learned more hurtful information.
In your shoes, I would go ahead and schedule a polygraph. There is a pretty stereotypical pattern in which the WS tells just enough to "get out of trouble" in the moment. In other words, the information you've just learned likely is not the whole truth.
For me, infidelity was not the dealbreaker. It was the lies and self-protection (and protection of OWs, at my expense) that put the final nails in the coffin.
Your husband may not know how very detrimental TT is to reconciliation. He may be doing what many do: offering info in little dribs and drabs--telling himself, after each revelation, "See? Look at her response! If I told her everything, she [fill in the blank]." (The blank might be filled with, "would divorce me right away," "couldn't handle it," or any of a million of rationalizations used to excuse TT.)
I would tell your husband that you appreciate that he offered new details, but that, given that he only did so when a polygraph was being discussed, you are not confident that you have the entire story.
I'd ask him to write a timeline---starting with the very first boundary he crossed (whether it was talking himself into saying hello to another woman, or giving himself permission to make a work email a little too personal, or whatever), even if it involves women you do not yet know of. I would ask that he list, chronologically, EVERY instance in which he was inappropriate with other women (or men, if he has talked badly about you to friends--an action that represents betrayal and paves the way for infidelity), and once he's completed the chronology, to go back and fill in details: what happened (including graphic sexual detail), how he felt about it, how he justified it in his mind, what he told you he was doing during those times (my husband, for example, used "job interview" and "business trip" and awful lot).
Tell him that you expect a bare-bones version (perhaps just the chronology) within a specified time frame. Let him know that you expect him, for the rest of your marriage, to fill in the details as they come to him (because "I don't remember" is common and, quite probably, true---but the more he examines his actions, the more he will remember).
And then tell him that you will still schedule a poly.
He told you more, but the odds that he told you all are slim.
And you just can't reconcile---move forward constructively in a new marriage--if there are secrets and lies forming a barrier between you.
