"don't worry, I am going to his house to study and we already agreed there will be no sex today" This was priceless!!!
You should have told her your brother acted they way he did because he has rightly lost respect for her. She is screwing a 60 year old man (who she knows only wants one thing and seems ok with that) and does it in his your face. But then strings you along by keeping your hopes up that she might leave OM soon!!!
Just curious...how many times has she said this??? And how many more "study sessions" with OM before she makes a decision?? Or better for you to make a decision? I am not trying to be mean just trying to throw some cold water on you!!! Do you really think that if you pulled back from her until she makes a choice that she would actually choose OM over her kids and you? The OM at 60 years of age wants nothing to do with 5 boys that will hate his guts and be in his way. He just wants a booty call with no strings. Your wife seems OK with the current arrangment and by you sitting back and not rocking the boat it is perfect for the OM. He knows once you force the issue she will have to choose between destroying the lives of her children and becoming a part time mom or keeping the family together. Its time to stand up for your family and stop the madness. Her relationship with the OM is a house of cards just blow hard enough and it all comes down and he finds someone easier to play with. Good Luck.