The one thing that you really need to remember here, is that when your S is having an A, they reaally aren't thinking all that straight. They are hiding and lying, and have guilt in there as well. They will blame you, do things to fuel their "fire", anything they have to, to justify to themselves that what they are doing is right. Once the A has ended, those lies come back to haunt them and they tell more lies.
Basically, you just have blow the lies away, and accept that they are/were part of the spouse's justifying their own actions at the time, they are a "side effect" of having an A. Deep down, they know it's wrong, so they have to find anything and everything they can to make it seem like they are doing the right thing in their own minds.
Never try to figure them out, you will go crazy trying to.
