he will blame, he will complain, he will make things up, he will rewrite the past. this is what they do.
i called it Making a Monster, my x was telling everyone what a bad husband, father, person i was, i was abusive, she'd twist stories to make me out to be a monster. not because i necessarily was, but to simply justify her actions - to herself and others.
cheating on a normal but flawed person is bad, everyone agrees to that, but cheating on a monster is good - a person deserves to be happy and to "escape a monster" is noble and the right thing to do - friends and family support it, there's no guilt in that.
but its not real.
so you need to protect yourself from his spewing. ignore it if you can, walk away from it, etc. and then go do something positive for yourself.
"In a ham and eggs breakfast, the hen is involved, but the pig is committed".