So sorry about this, what a terrible situation to find yourself in. I have never experienced this myself, but as far as I am concerned, the breaking of trust would be the end of the relationship, along with the the constant denial and accusations that you were imagining it. I could, possibly, forgive a sexual fling if it was admitted, but the lies and deception are beyond it for me. Every time he goes to play golf/go away on business/go to visit an elderly relative you are going to wonder, you are going to be checking up on him, and you will turn into a person that you won't like, suspicious, mistrustful, checking up with friends.....do you honestly want to spend the rest of your life like that? Keep the anger, and use it to your advantage, get your financial affairs in order and think about what to do next. You don't need counselling, you need legal advice. Do his work colleagues know? Are you always going to be wondering who knew and whether they felt sorry for you? In the words of Mumsnet, GROTB (get rid of the bastard). Make a lovely new life for yourself, and leave his mistress to look after him in his old age. Don't make excuses for him, he has betrayed you dreadfully, possibly out your health at risk ( he is a liar, do get checked for STD, why believe him on this?), and he has ruined your future life together. You can never, will never, and should never trust him again.