50:50, so you get the children and he walks away without any parental responsibility and half the money? Okay then, Mr Man, see how that works out for you.
He's coming up with every excuse in the book for why he's been a cheating fucker, isn't he?
From what you've said, he's never parented the kids on his own, he yelled at them all the time, you've all been walking on eggshells, and now he's cheated on you and walked out.
But he's a people pleaser, is he? Just wanting to make others happy, very passive sort of guy, never had anything for himself? I note that you have absolutely no money...so where is the money? Can't be with Mr 'I never did have anything I liked', can it?
You didn't support him properly, you were stressed and didn't give him enough time - but at the same time you mothered him, moulded him, did everything for him? So he had to get away to get space?
He's a fuckwit. And there is no way, NO WAY, that he only developed feelings for the OW the week after he left. He left because he was cheating on you, with her.