Kenickie I suspected you would say that the therapy concentrated on relational causes and I'm interested that you both felt that this wasn't the issue. I'm curious too, how the therapist dealt with the issue of his continued friendship with the OW?
Given the circumstances you describe, of course you are stuck. If the biggest change to have occurred is to your behaviour and the hypervigilance you describe, this is not progress at all. You cannot go on policing his fidelity, because this will make you feel worse and the reality is that none of us can prevent infidelity in another person.
If he still thinks the cause was your absence - and you rightly disagree, then there is every chance this could happen again with someone else. You are no further forward in determining the cause of this then you were on discovery. You perhaps have uncovered that his childhood produced a lack of boundaries and therefore a personal vulnerability to infidelity, but your H doesn't seem to have bought this either and is stuck in a script of this infidelity being entirely circumstantial.
Plus, if the therapist ignored what s/he managed to uncover about his personal vulnerability and reverted to the "safe" hypothesis that this was relational, I can see why the therapy was less than helpful.
Try to project what you would need from him to restore your safety, lead you to think that he has found the true cause and made sufficient changes to his character to ensure this can never happen again. Write those behaviours and actions down. There is a sense from you that he has never "got this" at all and that you are angry with yourself for not insisting on certain conditions and behaviours before you would continue with the marriage.
Try to think about all the possibilities, if you are feeling stuck. You don't have to stay in this country, you don't have to stay in this marriage. It is also not too late to insist on some conditions and changes. You have more power than you think you have. There is also a sense of your H not taking this (or you) seriously enough and believing that you will not end this marriage, especially because you have so recently faced upheaval and moved to a different country.
Time to wake him up to the real consequences, do you think?