Here's what happens -- WAS needs your pursuit. It's comforting for them to know you want them so they can come back at any time. They are motivated to keep that safety net available. When they sense you pulling away or don't know what you are doing or thinking, they get nervous and will start being nice to draw you back in.
As soon as you let your guard down they will again start to distance themselves from you, either with negligence or nasty or uncaring remarks. You must let them know you want them, but you can't come too close.
This is not sinister mustache twisting behavior, they don't know why they're doing it. Usually they are conflicted and as long as they can keep you on the line they don't have to face themselves or make any changes. The longer they can put off disappointing either you or OW the better.
Your exploding on him probably triggered this, your distance got too great and he started to worry that he was going to lose control. As soon as he is convinced you're back you can expect him to start distancing again.
If instead you keep distancing, you disrupt the push and pull dance you're locked in. You need to make him wonder what you're thinking and what you're going to do. Go out and don't tell him where and see what happens. You'll get him to pursue. Be nice to him and you'll get him to distance.
Your way out is to apply distance yourself and do not relent until OW is gone.
Accuray
Married 18, Together 20, Now Divorced M: 48, W: 50, D: 18, S: 16, D: 12 Bomb Dropped (EA, D): 7/13/11 Start Reconcile: 8/15/11 Bomb Dropped (EA, D): 5/1/2014 (Divorced) In a New Relationship: 3/2015