@Calforniansunsets how are you today? Did you sleep? Do hope your doctor gave you some sleeping tablets and was kind to you yesterday. You need sleep and lots of water to replace those tears, to process and get better. Christ only knows what makes these men so bloody ridiculous and PREDICTABLE. So dull and WEIRD and drama queen but ultimately damp squib level disappointing and yet they think they're the only ones in the world going through this... Yeh yeh yeh and yawn. So much collateral ireparable damage when they are just so pathetic really.
I PROMISE you it does get better, and in ways that you can't forsee or imagine now. Look up trauma bonding and the effects of abandonment as they have a very real and negative impact on the way you will recover and look back at your marriage in hindsight. Even PTSD. It takes a while for the heart to catch up with your mind and harbouring feelings of love is to your credit (not his, he just does not deserve your love but believe me he'll take them and boost his ego - 2 women in love with him! WHAT a GOD!!) but those feelings are not to your benefit in terms of recovery.
Don't believe a word of what he tells you from the day he left onwards. He is consumed by guilt - for now - hence the anger, and blaming you is the easiest way to make poor Diddums feel better. It is all rubbish of course, no one is perfect but if you were so awful then any man of integrity as he likes to see himself! would have talked to you and you would have worked it out together. But he didn't do that. He snuck around behind your back with his mistress, then decided to throw a hand grenade into the heart of your family, and has now gone off for a life with a much younger woman with clear daddy issues!, a very very weird dynamic with her age/being his superior at work, and a five year old to annoy him daily to boot! Lets hope that poor damaged child gives him hell. He'll come to understand the phrase be careful what you wish for! And I can only imagine the gossip at their workplace. Even if you were that way inclined, you wouldn't have to do a thing to tarnish his reputation, he's done all himself already, and of course you are entitled to tell anyone and everyone how appallingly you've been thrown over if you want and need to.
In these early days, you need to get it into your head as quickly and firmly as possible that he is not your friend, has no loyalty to you at all and will just lie if you put him on the spot aka very reasonably require some sort of explanation from him. I just wouldn't talk to him about anything other than child arrangements if I were you. He has put you and the family into a separate compartment in his head, and now everything he says he has probably just made up there and then, but you will be inclined to take him at his word, in particular criticisms of you and what he wishes (only now) could have been different and then it will just eat you up. This is definitely no longer the man you married and you need to really really know that in your heart as well as your head.
You do know you have his best years and an awful lot of them? Perhaps he is starting to go a bit bald now. You and he have all the history, first love, first times, the joys and innocence of youth? The memories of him with hair!, the children together without the baggage of earlier families vying for attention and time. She, and the ones that will surely come after her when she's bored of him being so old and tired!, will never have that long history. He'll carry a lot of baggage around for the rest of his life into every new relationship. [NB - Don't feel sorry for him he doesn't want it or deserve it.] His character has changed in a fundamental way for whatever reason, and the old him that you knew and loved just does not exist any more. It is as if an alien has taken his place and is wandering around looking just like him but is as detached and cold as ice. The man he was, is gone and will never return, I'm sorry, even if the new alien version of himself temporarily changes his mind in two or three months, (which is the usual time for that scenario to play out I believe).
I advise you to keep a diary and write down everything you feel every day. Your mind plays tricks on you and even years on, something small could potentially jump out at you and momentarily set you back. Grief, for emotionally that is what you are dealing with here, goes in cycles with many repetitive phases of one step forward, one step back before you arrive at full acceptance. Which you will one day. Re-reading your diary will distance you from the despair you might be momentarily feeling, and help you remember and reinforce positive ways of thinking and viewpoints which have helped you before, so speeding this process up.
I wish I had found Mumsnet in those days after it happened to me, no explanation, ExH just upped one day and left. I constantly thought it must be me, my fault, and my mind would torture itself going round and round and round - if ONLY I had done blah, reacted differently to blah etc etc. (Actually, you'd probably just do the same again in the same historical circumstances, but this sort of shocking abandonment leads directly to your developing the equally shocking behaviour of a doormat if you were ever to accept him back again. No one, especially him, more importantly you, respects a doormat.) You need to be able to read your diary looking back at better days when you were writing in a more positive frame of mind. It will help pave the building blocks that slowly lead to your recovery. You WILL RECOVER my lovely, I promise you that. I'm not going to say how this situation is 'all so positive' and how 'everything happens for a reason' etc etc - god how I hated that when all I wanted and all I could see was what I'd lost and couldn't have.
As time goes by you look back at the relationship with clearer eyes and you'll start to remember things you may well have suppressed at the time. That is what happened to me after a few months - when he left I couldn't peel myself off the floor with the shock of it all as I'd thought we were so happy. I'd 'forgotten' that he'd been weird, snappy and distant for a year or so, it was just one of those things and would all work out in the passage of time, I thought; these things happen in a long marriage. So immediately after he left, I felt that if a large truck were to have been coming down the road when I was crossing, that I wouldn't have been in any particular hurry to get out of the way, and almost wished that something like that would happen to make that all consuming pain disappear... But I would never have proactively done anything to myself; like you, I had kids - although they lost their mother for a long time. I'd disappeared into myself and was a soggy crying heap whose idea of looking after myself by remembering to eat a laughably small amount of food even once a day was a joke that would have been lost on me at the time. I'll be honest, I still love him now, 8 years on, but not in the same way, and it is more a testament to my good character than his! With time it came back to me that he'd stolen a large portion of the family money I had inherited in a really underhand and sneaky way, taking advantage of my online ineptitude. After I'd discovered this betrayal about 7 years before he left, I'd suppressed it, he'd minimised it and I never told a soul at the time out of 'loyalty' to him. It was only a few months after he left that I even remembered that incident! There will be things like that for you, and it is a pretty handy thing to remember when I might forget that really, I dodged a bullet. So if that truck had happened to come by it would have been a disaster and a complete waste, as he so, so wasn't worth it. No man is, especially one who would do to you what your husband has done.
Time will detach you from him. It just isn't possible for the human psyche to go on feeling the level of pain you are now feeling, constantly. It will take some working on, to avoid the traps I have mentioned, where your own mind will be working against you, but you can do it and you will get there, and then your joy will be your lovely children which is actually a much better and more fulfilling kind of love. Men are replaceable, children aren't. I'll stop going on now, but I hope some of what I have said will give you hope.