The worst thing of my life. I thought I was going to die from the pain. Heartbreak really is physical. Both my parents died at this time - both of them! - and it was nothing compared to the loss of the person I had chosen to share my life with, who I thought was my friend, who I chose to give my trust to.
Why does it hurt more than anyone who has never lived it can fathom (I had no idea before)? Because of the lies and the hidden secret facet to him, this person I thought I 'knew'. Because I don't know what was real and not real. Because I was THAT replaceable. Because he isn't who I thought he was. Because we didn't have what I thought we had. Because, actually, I don't know him I just made assumptions. Because I am Fallen (the scales have fallen from my eyes and I am no longer innocent). Because of my humiliation. Because of my shame. Because I look at my innocent friends as the outsider and see their innocent security and listen to [ie, how wearing an old t-shirt to bed doesn't matter/putting their H down] their assumptions and think, 'you have no idea of your husbands secret thoughts, feelings and life' - its awful! I am the outsider.
Because I found out that even though I was despised and mistreated whilst compared with imcomparable OW I still had my uses as housekeeper and nanny and so shouldn't be got rid of. Because I find his ability to split himself (talking to OW on the phone, then phoning me, buying us both gifts) quite frightening.
Because now he finds my rage unacceptable and 'hurtful'. Because he thinks it is very unreasonable of me not to accept his explanation that it was a 'mistake' and 'didn't mean anything' and 'wasn't a relationship' even though he chose being with her right up until he got caught, and that he doesn't have to answer my questions, and 'why aren't you getting over this YOU are the problem'. Because he is still not sharing his truth. Because he used another woman (although being married with children WAS a big fat CLUE) and screwed us both over.
My husband has been diagnosed as a narcissist, but I am suspecting that Midlife Crisis and adultery have huge, huge elements to narcissism to them. Not all men cheat. But you do have to be incredibly self-absorbed, feel very special and ENTITLED to think the rules don't apply to you/not care about people you are supposed to care about, in order to develop a secret life of self-gratification.
So, to the OP: it is agony. I think you must (with hindsight I should have done this) act decisively, find a therapist who understands infidelity. Ask him if he is aware of Shirley Glass, Peggy Vaughan, Myra Hirshenbaum and Linda MacDonald [THIS IS VERY IMPORTANT, OTHERWISE YOU WILL GET THAT MUMSNET GUFF about forgiving* and what needs did you not fulfil? (old fashioned and minimising)], who will help you with your rage AND require him to face up to himself.
*I do not think my H's IC (old fashioned) is helping at all. She told him that he shouldn't traumatise me by giving me details when I asked for them, which has basically gave him carte blanche to shut down, and that my rage is unreasonable and over the top, and she told me I should make him 'feel safe' enough to share. So, I must nurture him!!!!!!
When actually, I think 'this is your consequence' and 'you must tell her if she wants to know, it is the only way she will get over it' and 'healing is hard work, this is what it takes, to listen to her pain that you caused' is what I THINK he needs to hear. But hey, who am I, just an unqualified person with hurt feelings and broken trust.