I'm sorry you're upset.
I don't know your story, but it looks like you're separated. Was he promising to work on the M during the separation? Very gently, if you are separated and he's done nothing to show that he's remorseful and wants to fight for the marriage, then his behavior is not shocking. If there has been no work toward R but you were tracking him, stop doing that for your own health and healing.
On the other hand, if he was promising to try to R and promised NC and all the rest, then obviously, you have a perfect right to be fuming right now.
There are 2 issues that pop up as a result of his breach of NC with the OW - #1, what are the consequences that he will experience from you? And #2, what are the consequences that he will experience from work?
My exwh had an A and is still with the pig who was hired to be his very own secretary. Talk about a sexual harassment lawsuit waiting to happen. At the time that I found out, I never made a point to call the HR department or any of the senior partners to specifically "out" their affair. My feeling was that I didn't want him fired because I wanted him to have an income and pay me child support. I also wasn't going to give those two numb nuts anything to bond over - these idiots bond over the crazy wife yelling and screaming and making public scenes over their "luuuuvvve" I wasn't going to give them that. I wanted the natural consequences to take over and, if you read my latest post in D/S, you will see that karma hit them both hard in that office after the whole thing exploded.
Besides, I also figured that most people in the office already knew. They were there every day watching them laugh and take their lunches together and leave the office together. I was most likely the very last person to know, so me blowing the lid off of the whole thing would, in reality, be more like blowing a tiny popcorn fart.
At this point, focus on yourself and how you are going to handle this latest infraction. If it's with a D, get your ducks in a row, call an attorney, and go NC with him.
I know how you feel though - it enrages you and you feel like there is no where to turn. Come here and we will listen.