Neil, so sorry you are faced with this. It’s horrible.
but I guess the only way to go is to separate the two. You want to be a better person to be a great dad for your kids and for your own self respect. Concentrate on that. Focus on making their Xmas as good as possible and take pride in that.
Either your wife will realise what she’s lost or someone else will see you being a great dad. Or both 😊