Good morning everybody thank you for all of the replies, I'll try to answer all of the questions. I'm on my phone so it might take a while.
What is he doing to save the marriage himself? Nothing huge. Exactly like a PP said I get the occasional bunch of flowers.
Does he seem remorseful? I would say no as a whole. When he was pushed to tell me (by the OW who believed he was leaving me to be with her) he seemed annoyed more than anything. He didn't want to be having the conversation and felt put upon that I had questions. He appeared visibly inconvenienced and irritated more than remorseful. When I agreed to stay but said I needed total transparency I explicitly remember him saying "well it feels like I'm just starting a punishment"
I should have ended the marriage there and then in hindsight.
Truth be told the affair was such a shock to my system that I immediately went into autopilot family preservation and I just wanted her gone and him home with me and the children. Much to my shame i did do the pick me dance and me feigning interest in lots of sex now is just an extension of that. My mental health was crippled in the aftermath of the affair and I felt desperate to keep him close as I was in such a shit place I didn't feel as though i was enough for the children.
He showed what I think was genuine remorse a couple of months later when I sat him down and said it needed to be discussed. When I asked everything I wanted to know and told him how badly he had hurt me he did get visibly upset. I asked why he didn't appear remorseful when it came to light and he said that was because it wasn't what he wanted in the first place and he was being blackmailed into coming clean and leaving to be with her. (This is true and I saw the evidence in the form of messages demanding that he tell me and go to her house as planned otherwise she wouldn't spare me the gory details)
Some of the lies and stories he span to cover his tracks when the affair was going on are out of this world.
At the point of the affair coming to light I was going through a frightening time with my health, I was under investigation for something which could have turned out to be life limiting. He almost made me late for an important hospital appointment during my investigations and tests because he went to see her before I was due to see the doctor that day. He was supposed to be taking me but instead I had to get public transport as he was out with the children and the car, with her. My children were babies/young toddler so weren't able to tell me anything.
His sex obsession is OTT in our household, He expects it at unreasonable times for example when I've just got in the door with shopping or whilst dinner is cooking. There is no romance just a cheeky "get in there you" with a wink, that he thinks is going to make me want to stop what I'm doing and run off for a quickie.
The thing is this was the norm during the early days, we were very young and had no children, but whilst I've discovered that things do slow down, he has not.
We're still young (under 40) but as everybody has said having going children does slow things down for us normal folk.
I agree there is a sex addiction at play, some years ago he admitted to being an over user of porn. The signs were all there which I ignored at the time because I was in denial. He is a pervert, the type who sends pictures of his genitals.. that type.
I foolishly allowed myself to fall for the daft, soft, funny and kind side of his personality and embraced the sex drive.
He is an adequate father, he is hands on yes but can be a bit inpatient sometimes (never aggressive or abusive)
He does think I'm enjoying the sex and always wants foreplay to be a part of it. I've mastered the art of taking an orgasm within 5 minutes and he genuinely has no clue that it's not real. I have to my disservice allowed him to think that I'm up for it as much as he is, this was part of the pick me dance. Me trying to make myself seem like the better option.
I do worry he will do it again, it feels like it is inevitable. The colleague he had an affair with is definitely nothing special and while I'm only average looking I do take care of myself and have some things going for me.
If he will embark on an affair with somebody like that when there is not much chance he'll turn down somebody young and attractive If they were interested.
He feels like a paradox with two conflicting personalities, on one hand he's a "big softie" with a lovable personality, he can be sweet and flattering, a bit cheesy in an endearing way, he puts me before himself in all situations aside sex - then on the flip side he's an over sexed man child who is very selfish, a terrible communicator, self entitled, and a sleaze.
If anybody here watches Hollyoaks then he is just like Darren, reckless and emotionally immature.
I've read the cheaters script and it is all ringing a bell. I spent some time on chumplady in the early days.
I've actually been receiving counselling on my own as he said it's not something he's comfortable with. He doesn't know how to talk about his feelings he says. My therapist thinks I need to concentrate on rebuilding my sense of identity with a view to separate later on, and do so when I'm at a point that I feel able to cope on my own (which I doubt sometimes, because I have depression)