My H was one of these new age dads, was really involved, took care of the kids on his own in the evenings, because of my job. He put them first, always, made sure they had lots of love and attention.
Then the A. He was a completely different man. He wouldnt even call to them good night when he was out of town, would go days without seeing or talking to them. Was really an ass, short tempered with them, mean to them etc.
So glad he figured it out. He is a great dad again, his kids get all the love, and support, but stern guidance that they need. My 14 yo daughter hates him, as most 14 yo girls do. My son gets aggravated by his demands, but is starting to get that he is tough on him so that he becomes a great man.
Through the A, through the turmoil they were my bright spot each day, they were small then, and I loved on them, cuddled them, and made sure they felt safe. The oldest one knew something was wrong, and I think he sustpected we were heading for a D, but he also knew Mom would always always always be there for him.
It's tough, but they have to be put in first place even through the shitstorm of infidelity.