Thank you for your reply. My name is an indication of where I was born in the UK; but more than happy to be associated with a four legged friend.
I think what went wrong was quite simple and probably cliched. We forgot about each other once the kids were gone and took each other for granted. I was promoted and very engrossed in my career (to fill the gaps in life I expect) and didn't notice that he was struggling. I should have been there for him; but I wasn't. I acknowledge my part in the vulnerability of the marriage but after 30 years together, maybe he would have said something rather than look elsewhere. That's on him, not me.
A couple of months before D day he did say that he didn't know where he fit in my life anymore, or if I needed him. Guess what the OW is very needy and has small children, so is always at home when he decides to call in. He likes to'sort' her mess out and look like a hero. But why he has to feel 'needed' and only feel self worth in this way is not something I can sort out for him. He needs to have some self discovery himself. Time apart is something I think is necessary to clear our heads; the problem I think is that even when they break up, she is back on the phone within days.
There have been times when he seems more grounded and has told me what the relationship with OW is and how it is toxic. But, after they last broke up and got together again, I reminded him of what he'd said and he suggested that it was different this time because she felt that they might have a future now. She is totally controlling this infatuation that he has with her. This is why I have totally backed off a game of tug of war. It's undignified for one thing.
Now i'm not performing in the circus, I feel a great weight has lifted. No more anxiety, no more tears. I chose for 27 years to mould myself to his and the families needs. It was my choice and I wouldn't change it for anything. 3 wonderful sons was the reward. But, I'm now doing things solely because I want to and it feels great.
I'm also self aware enough to know that I am more than capable of putting a shield around myself to control my emotions. I do it every single day in an emotionally challenging job (I investigate unnatural deaths) I am worried that whilst I sort out what I truly want, the impression that I give to him is one of 'oh well I was right' she really doesn't need me and is happy whereas he is unhappy.
I have of course tried to explain to him that I don't 'need' him; but want him and that happiness is within and he shouldn't be looking outside of himself for happiness. But needless to say it fell on deaf ears.
Self discovery via distancing is very revealing, but I'm not sure what it is revealing is beneficial to the marriage. I'm starting to wonder how we stayed married for 27 years!!