I'm going to ask her if her kids have the same father. Is that too nosy?
Why do you want to know?
Because I can't believe anyone would want to sleep with her twice.
That's certainly rude to say. Don't you think that's too personal of a question?
It's not like she doesn't some idea that her husband is cheating on her.
Regardless, you don't need to pry into her business, especially in such a rude manner.