You are right, your kids will eventually learn about your H's affair. And I'm sure they will know that you were just trying to spare their feelings. I just worry what message this sends kids about marriage. Marriage is a big thing, it is supposed to be a lifelong commitment. You don't just leave when someone 'better' comes along.
PM,
Your husband is a terrible father right now. The best father is one that respects and loves his kid's mother. Divorce harms kids. And a good father will do everthing humanly possible not to harm his kids. Check out the The Unexpected Legacy of Divorce and see the outcomes the researcher observed . . .
He will never find longterm joy in someone else. Eventually he will ge tired of her as well when the chemicals of infatuation wane . . . and they always do.
And you are not disposable. You will meet a worthy man that will love you to death. Perhaps it is best that this one is going.
I'm a man . . . But I can change . . . If I have to . . . I guess . . .