The key is to take the emotion out of it. Easy to say - NOT easy to do.
You asked if anyone else was in this situation and how it turned out.
My ex was also a "recovering" alcoholic with an OW. We were together 30 years, married 25 - I could not believe he would toss aside the kids and I for a brief fling. But these 2 were co-dependent and she was a predator. My M didn't stand a chance.
I stuck with the negotiations and cried through so much of our mediation. He was cruel and said stupid, mean things that went down on record. He went for ridiculous things (I lost on those) and gave in on more important things (again - STUPID). You will lose some, but you will gain some as well. DO NOT GIVE IN on things you are entitled to unless it is part of the negotiations and your L advises it.You have to live with it. If you are entitled to support - do not give up. If he does not sign in due course he could be held in contempt.
Don't expect change. I think they pull away from the life they knew as they feel they have to. If he doesn't see his son - it is his loss but it is also horrible for your son. Help your son remember the good things about him and assure him that you are there and love him and that you hope his dad will come around in time.
Does time change them? Yes, I think when the heat of it all has died down - they do have some regret and the anger subsides.
My ex began his affair app 11 years ago - just as we were celebrating our 25th. He was gone shortly after following a DUI and me figuring out about the affair. It took 5 years to get our financial agreement/divorce. Then I just avoided him for 5 years and the kids did what they could to have some kind of R with him (limited). Then our disabled son suddenly became critically ill and I was told he would likely not survive. So I called him and he came. Hugged me. Met my new man. My siblings who were there told me they had not seen him in 10 years. It was awkward for all of us but we got through it and since have maintained some kind of respectful communication regarding son.
Do I think he will ever be the person I knew? NO. Do I think he got what he deserved? YES Do I have regrets? Yes - but I do think that I did what I did at the time to protect my family. I regret that this happened to me but I now know that God had greater things for me. And I am enjoying it and the freedom it has given me.
We can't control someone else. I hope for you that you can reach some resolution soon. I would be pushing my lawyer to do better for me if I could not get this resolved.
Sorry that you are here but know that it will become a distant memory soon.