@1forAll74
I have known a couple of spikey and grabby women, who were only interested in the money that their Husbands had. They did not work, and a credit card was their only love.
This. It's amazing how blind people on here can be at how uncaring some can be on their marriages.
This woman has told op she doesn't care about their relationship, their marriage. She only cares that he funds her lifestyle. She loves money, not him. But yeah, totally don't understand why he'd want to leave her. 
She's also now got him paying her money still that she has clearly shown proof to op that she doesn't spend on their kids, but on herself too. None of you find that selfish, being mothers yourselves? I mean OK I doubt the kids are starving while she drapes gold over herself, but it is quite selfish.
She is also now shagging a married man, and getting gifts from him. Would any of you still feel sorry for her if that happens to be your husband? She is shagging this guy for money. Again, doesn't like or love him, it's the money and presents she loves.
God knows what's actually happening with the kids now, assuming she is looking after them. She's got the house, she gets cm, she doesn't need anything else. But that's his problem, he should grow a spine and take the divorce to court and see what they say, not bend over for her demands. I doubt either he was clean in this whole thing, neither of them sound very mature, but I'm not feeling sorry for either of them. She's grabby, he's an idiot.