She's not an amazing wife and mother. She cheated on you then lied in such a way to generate sympathy from you for cheating on her. Most of the time this isn't something that just happens once either. By staying with her all you're doing is telling her, you'll put up with that kind of behavior again.
Ok, I don't think it's irrational to want to, I think it's irrational to get married now. Wanting is normal I think.
She's not an amazing wife and mother. She cheated on you then lied in such a way to generate sympathy from you for cheating on her. Most of the time this isn't something that just happens once either. By staying with her all you're doing is telling her, you'll put up with that kind of behavior again.
They’ve been friends 17 years. That’s an awful long time to pretend to be friends. Have you ever thought maybe they were friends.