Sorry this may hurt your feelings but I think she is having affair at work.

She may think that she is the breadwinner, she thinks she doesn't need you since her pay is higher. But fact of matter is, nobody raises the kids as good as you do. She needs to realize whichever guy she is going to bring home, he is going to fall short of you in impressing the kids. Even if she divorce n raise the kids herself, she will struggle.