One thing I can tell you...is YOU NEED TO GIVE HIM TIME TO GET OVER HER!!!
My H had an A...he was talking marriage...he thought he truly loved her...he left me and the kids over her...when he did return he couldn't tell me he loved me...I realized after talking to his sister that it was going to take time...he disclosed to her just months before returning home how much OW meant to him...when you "think" you love someone it will take time...
With you H he probably feels like her saviour...see her H died...he stepped in to save her...protect her...he needs to have someone take that role from him because he doesn't want to hurt her again...I know it isn't fair that he is hurting you and not really seeming to give it thought...but he depends on you to understand...again not fair...but that is how it is..
My advice is give him time to "unlove" her...give him time to let go of her...hopefully she will find someone once he is physically removed from the situation...then you can set future boundries...like if it comes up for him to return to work there for a "short 2 weeks" tell him NO...if he leaves he moves out...you won't go down that road a second time...if he has a choice of work locations he needs to excercise that right to protect the family...but again...getting over the OW takes time...it isn't as easy as flipping a switch...being home doesn't make it go away...being in contact makes it last longer...but give him time or you will drive him right back...
It took my H over a year after returning home to tell me he loved me...and it was almost 2 years after OW was out of his life...so, it does take some time for some people...
Hang in there...take care...and DB...you will be ok....LIN