One thing I have noticed about all cheaters is that they are inately selfish people who take.
So ingrained is their selfishness that they have no concept of the pain of others.
Long marriages with these types usually have partners that are deeply caring who have accomodated their partner's needs, so much to the point that they in fact shield them and protect them from aknowledging their own selfishness, if that makes sense.
Basically an empath who protects the reputation of a deeply selfish individual.
I should imagine op during your marriage it has become harder to not see his selfish nature.
Honestly I've seen women who have championed how wonderful their husbands are, how much they do, how much they provide etc only to really see that it was only all for themselves, they rarely do something unless there is a payoff for themselves in some way.
This man feels entitled to take what he wants, he has no concept of your pain, it would be pointless to expect mercy from him.
This is the real man, an empty shell with no understanding of real love, the only saving grace in this is his ow will have the same make up as him, she is not a carer, an empath, she can't be as she could never harm those arround her like this.
They will be two shits together, whether they will last is anyone's guess, I would lay money on it not lasting but that doesn't help your pain at the moment.
One thing you will learn through this though is how to take for yourself, you will learn to prioritise yourself, your needs are important, learn how to be selfish.
He's an utter fool and has no idea what he has lost, regardless of the outcome, his losses will be significantly higher than his gains.
None of this is your fault or blame apart from the fact you chose a fool and enabled him to think he had a brain.
I personally think you did too good a job of looking after him, building his confidence and supporting him, he didn't deserve it, took it for granted but it looks like he's on his own now.
Pull the plug and take back the power, he won't get chance to feel that kind of support again, there arn't enough years left for that, I should imagine his older years are going to be quite uncertain.
Take care x