Have read the whole thread. Brought back some pretty hideous memories for me. My exH did the same. Only he went to Thailand leaving me with a six month old baby.
muckingfuddled's post is totally spot on. It's really really hard but do the things she has suggested.
Do not engage at. all.
Don't bother texting him back re counselling session. Don't get in touch with him or respond to anything at all.
Maintain total radio silence.
Change your locks. Change your will. Secure everything and anything you can financially - any savings in joint names transfer into a lone account for now. Ring local council and get single-occupant discount on council tax.
File for divorce immediately - the papers will need to be served on him. He will be told to pay all costs I have no doubt, when the solicitor is due to be paid on receipt of the nisi. File on grounds of unreasonable behaviour and adultery. You don't have to name the OW.
Keep your friends and family close and really reach out for support everywhere you can.
You will think and think and think and look back and wonder and piece events and behaviours together for weeks and weeks to come. This is normal and in fact helpful in some ways, as your brain is processing events and helping you realise, eventually, that none of this is your fault and that it would always have happened eventually happened because he cannot sustain a proper relationship. With anybody !
I hear and read so many many alarm bells and similarities in what you write about your husband - my husband disappeared for days or hours at a time in the years leading up to him finally disappearing. He had absolutely NO empathy. It was all about him. Everything. Right down to the type of car he drove and socks he wore. Idiot.
When I finally tracked him down and got an email address for him in Thailand, I was very factual and straight-forward. I asked him to please begin paying some financial support for our son. He emailed me back saying 'only once I know you have given my cookery books, my etchings and my bike, to my brother who will come and collect them'. WTAF? These men are children in adult bodies.
His cookery books were your husbands chutneys
It's hilarious now. It was bloody unspeakable, unbearable and mind-fucking at the time.
My h was also, on several occasions, as shitty as yours re being out somewhere, saying something hideous then expecting you to enjoy the day. It's a total mind-bender. We were on holiday together, in France, I was heavily pregnant. We were in a beautiful village on market day. I badly needed a wee and asked him to go into a cafe and check if the loo was a sit-down one or a squatty (no way could I squat). he was icy cold and said 'find your own fucking place to piss in'. He may as well have smacked me in the face. Then he proceeded to carry on as though nothing had happened.
Last thing I want to say, and I know there will be groans on this thread, but have you read anything about Narcissistic Personality Disorder? These creatures do a thing called 'Idealise, Devalue, Discard'. And when they discard, they just drop their partner like a stone, often stealing thieving and ransacking anything they can on their way out. They have no real emotions - they simply copy societal norms, hence the counselling sessions offer for example - he absolutely does not mean a word of it, he's just saying it as he knows how to pretend to appear caring or guilty.
I read up a LOT on this personality disorder (all these disorders are on a spectrum btw so he'll have a couple of other pathologies in the mix too). It helped me immensely. They are often very respectable people, charming, clever, knowledgeable and good at cooking. 
They are also shallow, cunning, obsessed with sex (quite often) and consummate liars and cheaters. They like to be married and have families because that makes their outer facade all the more convincing and 'normal' but it's just a cover for their vacuous inner selves, and their vicious streaks.
Your H has discarded you (I know that is very hard and painful and mind-fucking to read). He won't understand your pain because these Narcissists do not do pain. They feel the sum of fuck-all in the way normal loving kind people feel. They fall 'in love' quickly and at this stage are doing the idealising bit...but they starts devaluing that person when they realise she has normal human flaws or is no longer useful (sex life dwindles say, or she stops working and earning) and so they move onto their next victim, before humiliating and crucifying her in the end too.
They usually end up very sad, lonely, friendless old men.
Your H has already moved out and onto his next victim.
This is a Good Thing as you can now start to recover, and re-build your life without the daily anxieties of living with these fuck-ups.
So. Wave him goodbye to him metaphorically from the step of your own home. Shut the door, be with your cats (oh and narcs can't stand animals btw - they only pretend to like animals as they know this makes them appear nice and normal) Start the divorce going, communicate with him only through the solicitor and make sure he pays you off / that you get a decent financial package for yourself.
Sorry, that's very long. But I have walked in your shoes. btw four years on, I am happy as larry. My son is four and a we enjoy our lives, I am no longer the anxious shadow I was when we were married and I am no longer the sobbing wreck I was when he fucked off. I had my son (naturally) when I was 43 too - so plenty of time for you yet my lovely, to have children.
DO NOT ENGAGE. He's not interested anyway apart from the fact that any reaction at all from you will give him what is called Narcissistic Supply. Read up on it. I bet you see your car-crash of a husband there on the pages. (())