Pass, the money thing is very worrisome. I would protect everything.
Really I don't trust anything he offers until he's offered to end his affair.
It may not be the case, but the safest assumption for you is this :
"If he's not ending his affair, any act of cooperation is a scheme"
It won't be the case, but you have to assume that by default or you could get taken.
I think you need to reiterate your original position again. If you don't challenge the affair regularly addicts ahve this way of thinking "no news is good news". If you do'nt constantly challenge their affair they seem to get the idea you are "ok with it"...
This is partly why Tuppy reccomends protection phase of the confrontation, exposure, and interventions don't work... But in your case he relies a lot on the closeness and it does seem to have some impact on him.
But right now you cna't trust him as a partner. Keep the finances locked down and keep pressing the point of the cheating.
You have every right to ask that he pay for Retro if HE is the one bowing out.
Have you found a decent Family Therapist yet? If he WANTs to talk and express his feelings, the BEST course of action is to find him a healthy and professional OUTLET for that... right now he's just turnign to you or OW and neither of you right now are equipped to help him properly.