What on earth does he see in his wife? 
I just don't get it OP.
They have completely different sex drives, in fact, DW's is non existent.
She doesn't lift a finger in the house.
She doesn't work.
Actually, she doesn't do a thing.
I'm struggling to see anything aboout his dw that makes him stay tbh.
OTOH, He clearly has no respect for her, divulging details of her apparent failures to a sex crazed nymph who wants to rip his trousers off, has no respect for you, expecting you to believe these crap lines, plus he makes himself out to be a walk over imo. A man who disrespects his wife by cheating on her, but jumps when she says 'how high'??
I am just imagining their home life...dw lazes on a chaise longue all day, watching daytime tv...dh arrives home after a gruelling day to his wife's greeting of 'What's for dinner DH? Oh btw, the bathroom is looking abit grubby, and the waste disposal unit smells awful, I hope the damn thing hasn't regurgitated the food waste again, I haven't bothered to look, I was too engrossed in the tv to bother getting up and looking.'
DH cooks dinner, sorts out the mess, washes up, and then slides into bed beside his dw, feeling horny. She flicks the end of his penis hard, and tells him 'No darling, not tonight, after your last attempt at sex in 1997, I get flashbacks every time I see your penis...yuk!!, oh and would you get up early in the morning to run my bath before i go for lunch with my friends, I can't possibly have them coming here to eat...not until the house is spick and span...when exactly will you be doing that DH?'
DH takes the pencil out from behind his ear and scribbles 'Clean house until it's spick and span' in his notebook, before replying 'Oh very soon my love, very soon' before turning over and drifting into an uneasy slumber.
Now there must be a reason why he stays married to this woman..he either enjoys being treated this way, and some men do, or she is contributing something to the marriage that he wants/needs, or she is not as lazy/frigid etc as he is telling you she is.
Mind you, I don't expect you to do anything other than blindly trust him.
Also if you only wanted a shag OP, it would not register on your radar how much or how little she does in the house, unless it interferes with how often he can get out...I do believe most of cinderella's waking hours were taken up cooking and cleaning
.