Ladylovestocook another poster downthread mentioned a post I'd written on another thread, about mother-child romantic relationships. Here is what I said, slightly adapted for your circumstances:
"Have you ever considered that your husband is controlling? It's actually a very subtle form of controlling behaviour, but powerful in effect nevertheless. You might never have recognised him as controlling - or he himself - but it would be a good talking point at Relate.
You're describing a conflict of childish control methods and fewer that are associated with adulthood. The childish behaviours are laziness, procrastination over necessary but disliked tasks, sulkiness, disproportionate anger/irritation, refusal to engage in an adult dialogue (or engage at all), victim-focused behaviour and counter-attack. Put simply, these behaviours are about a refusal to take personal responsibility.
(Lady, in addition to the above, in your case there is also infidelity. This is yet another example of a refusal to take personal responsibility. Look at the story your H is giving you - the affair was a symptom of how unhappy you've made me....
What might be the adult response to such unhappiness? To discuss it with one's partner and express those feelings? To feel alarmed that one is developing feelings for someone else and resolve not to muddy the waters with a new love interest? This is how an adult would respond.
The child, on the other hand will do none of these things and will go on to have an affair. He will then take no responsibility whatsoever for the affair, lie about his own role in it and stick his tongue out at you and say: it's your fault, you made me do it.)
Before his affair, what has confused the issue is that you may have been enabling his behaviour by infantilising him to some extent - and so in effect, you have become his parent. Your behaviour then becomes more visibly controlling, so you complain, make repeated requests, take control of things that haven't been done, re-do tasks that have been botched, insist on discussing his faults and at its worst, treating him with contempt.
To outward appearances, it can look as though you are the more controlling of the partnership, but the reality is different.
What you're both doing is perpetuating a dance, or a script that put simply, characterises a rebellious child and an angry parent.
People who display childish controlling behaviours tend to be emotionally retarded by definition (they have never grown up or learned to express feelings in an adult way) and they lack emotional intelligence - so it can seem an uphill struggle to get them to engage in the first place. A third party like a counsellor can be very powerful in situations like this.
If you have become that angry parent, I'm sure it's a role that you didn't want in a marriage of two adults and you may see it as the only response possible if anything was to get done - I understand that. However, the counselling might also get to the root of why you chose a parental role to cope with the situation - and where that behaviour was learned."
Lady - what's needed here is for you to get tough. The disclosure of an affair is often the only calalyst that produces lasting change, but in your situation, we've got a very poor dynamic going on. Instead of it being you wondering whether this is actually the last straw and treating it as an opportunity to finally get your H to grow up, take responsibility and become an equal partner, you've got him reluctantly agreeing to "try again", foisting blame on to you and being wholly disingenuous about his affair. This dynamic needs to stop right now if there is any hope for your marriage.
In your individual case, I think your H actually needs a short sharp shock. I would be telling him that you have now realised the dynamic in your relationship and will not collude with it any longer. It doesn't matter what he admits to, you know he has been physically unfaithful and actually, this might be the last straw in a lifetime of childish control freakery.
If he wants his marriage, he must do the following: End the other relationship in your presence. Become an open book. Tell you the truth about it all. Go to counselling on his own and at the ripe old age of 47, learn how to become a man, an emotionally intelligent one at that. Take equal responsibility for everything in your relationship and in your lives.
Those are your conditions - and there is no room for manoeuvre.
Falter now Lady - and you will be mothering this man for years to come, but I will predict your future. He will continue to be unfaithful, either with this woman or with others - and one day, when he finds a woman who will mother him as well as you, he will leave you. He will also feel contemptuous that you sat back and let it happen.
Take control now - and you'll either get a vastly improved version of your H or you'll have a peaceful existence mothering only those who need it (your DCs) with enough time on your side eventually to meet an emotionally intelligent man who wants an equal partner, not a mother.