The fact that you love him and he's your favourite person in the world means, no offence, that you didn't have the measure of him though. You idealised him.
He couldn't act like this if he was a great person.
In my neck of the woods, we mostly see the middle aged and elderly men with their wives of 50 etc. years.
We occasionally see the mid life cheaters/leavers (not many though).
No-one respects them. No-one thinks well of them, a man who abandons his long term, faithful, loyal wife/life partner & mother of his kids for a new model. Forces his kids to live with it too.
That's what he is ..... So he's not one of the better ones.
He's crue too. Anyone with compassion and empathy would never have said "you have no self respect" when you were in shock, devastated, and in terrible pain; blind sided by something he'd been building up for months.
And as for the fact that his affair partner is a married mother of two young kids .....smh.
He would be considered a scum bag, feckless, having a screw loose, immoral, dishonourable etc. by the vast majority of people around your age that I know. There wound be nothing but derision.
I think you've had the rose tinted glasses on for him.
Why don't you make a list of things that are negative about him. Be very honest and critical.