Why the bun fights?
It's so predictable that on these 'affair' threads there will be a battle for one-upmanship' between posters. Some people should pop off to Saudi where they stone women who have affairs- you've the same mentality.
There is no certainty that anyone will find out about this affair. So everyone who is saying the shit will hit the fan when....just take a step back. I've known affairs taking place for years and the spouses have never found out. Nor have the children.
I've also known long term affairs where one or both of the spouses have known, and turned a blind eye. There is not just one reaction or outcome to affairs.
OP I'm not sure what you want from this thread.
You said that you 'need to end it all or this is how it will be' [no future].
What has prompted you to ask for help? Why not carry on for another 20 years? What's changed?
Is it that you have realised- maybe something has happened- that he will never leave his wife? I know you said that neither of you would leave your spouses- but reading between the lines of your posts I feel that you would, if only he would.
Is this right?
Or- if it's not that- is it your conscience?
Are you tormented by the deceit- or by the idea that you cannot have this man 100%?
You have 3 options:
carry on as you are.
End it completely
Leave your H and live alone with no guarantee that OM will leave his W ( at all of for you).
Make a list of the pros and cons for each and be honest.
The answer is within you- you need to find it then decide how to make it happen.
And I 2nd the idea of counselling- fantasies and affair type situations can suddenly feel very different when talked about in RL. You might find it the wake-up call you need, to get off the fence. And/or read a website called Baggage Reclaim- lots of good ideas there.