Smitty has had his fun. I thought I'd take a crack at answering his last letter...
Dear Happily Let off the Hook,
Your friend is half right. You need to talk to your husband about his infidelity, and if he does not change, then you must leave. It is more than sex. Though it is true that when he has sex with other women behind your back, he is fucking you. Your kids will figure this out eventually, if they haven't already. Then they will have to deal with a cad father and a mother who respects herself so little that she let it happen to her more than once.
You may need to sue him for support. That's the way it goes. If you don't want to deal with another man, don't. But in five years, you can either still be a shell of a human, or a happy and wise woman. The choice is yours. The flight to space is almost impossibly hard, too, but the view when you get there is , ahem, out-of-this-world.