I haven't rtft, I've only read your posts op.
It strikes me that your dh doesn't seem to be a serial cheater. He is a flawed human same as the rest of us and I could imagine that the combination of midlife, pressures on home relationship from parenting etc, a female being very keen and inhibitions being lowered by drink etc could result in a seriously bad decision.
Which is awful.
But, I think that he can either live a sham life and never tell you (which few people, and certainly none with a conscience could do without some kind of break down), or he just ends the marriage without giving you the real reason... Or he tells you.
If the two of you are to come through this, and I don't think that needs to be off the cards, you are both going to have to go through the mire, together, in different ways.
Which is ghastly.
But, there is no other way that doesn't involve the truth not coming out. Ignorance may be bliss, but the alternative is for a person, who has been a good human in many ways that matters, to carry a lie. For life.
You mentioned you were angry that he was full of bad feelings, but it is your feelings that count as you are the victim. Which is true, you are the wronged party and your feelings definitely do count. But how could he switch off the remorse and self hatred? Sure, the last thing you want is to be dealing with his bad feelings, but he'd have to be a psychopath, or place zero value on fidelity and you, to not have them.
So, you are both in a miserable place, on quite different trajectories. He, who has had remorse and self hatred eating away at him for a long time, is at a point where the weight of deceit is lifted. While you, are at the point where you have been plunged head first into confronting betrayal and loss of trust. The difference is like between long slow torture and being thrown into boiling water.
As a partnership, inevitably what one person lives the other lives alongside and this includes suffering.
I don't think he is a master manipulator of post-cheating emotion shifting where he feels better while you feel shit... That might apply to some men who cheat but who aren't deep down sorry. But
if he is a human who made a mistake and is sorry, he has to reveal this... Or the future is dead. So it is very reductive to say that by making you feel shit, he feels better and that's the point of it all and further evidence of his moral bankruptcy... Some men may intentionally manipulate like that, but it doesn't mean this is what he's doing. What else can he do? He tells you, this ends his big secret, if that wasn't a relief he'd have to be stone cold hearted. He's a human and should be judged on his own merits. From what you've said he seems genuinely remorseful.
After the paradoxical relief of revealing his deception, he has a long road ahead of self recrimination, re-earning of trust (if you decide to try to forgive), and life-long knowledge of what he put you through (assuming he loves you, which he seems to). He has to parent his children knowing he isn't a perfect role model. None of this is a small thing. I am not trying to suggest he is hurting more than you, just pointing out that the relief he feels now, is a blip in a long road.
Meanwhile you have your own distress, which is awful in a very different way.
When he did this thing he put you both here, it is self inflicted, that doesn't mean you aren't both hurting.
If you love him, and he is genuinely sorry you could find a way through this.
I know a couple who have done it, very successfully, it took genuine remorse from the guilty party, and love but it was worth it. They are both happier now and the honesty, courage and mutual support they used to get to a point where it didn't define their relationship was worthwhile. They now look after their relationship in a way that maybe they hadn't before, they know each other well, it wouldn't be forgiveable again but because the human frailty which got them there was an abject lesson for the guilty party which they will never forget, it is not likely it will ever come up.
You mention being disappointed he doesn't fight for you. But I think someone who feels they deserve to be thrown on the scrap heap would struggle to muster the self esteem to persuade you that he is worth keeping. If he is so appalled at his choice that he has wanted to end his life, how can he argue you need to give him another chance. To me I would be more suspicious of the depths of his remorse if he did.