did the wife know?

You're right, it did seem like she knew. I think she was very suspicious (i.e the scene where he puts her in a cab and chases Italia). However she didn't say anything possibly because she was expecting a baby?

Woman usually suspect because the man acts different. Usually wants less sex, but can act overly affectionate one minute then angry the next, caused by guilt. One minute guilty then trys to find a reason to blame you. This guy was obviously acting more distant. Sometimes women avoid confrontation until they have to because it will probably end the marriage, especially when she was pregnant. So many men cheat and often come back. I don't think she knew for sure but was suspious

I definitely think she suspected, and I think that's why she stopped taking her birth control. She did not want to have a kid before Timoteo's affair with Italia began. Once he began straying, she knew the best way to keep him was to give him what he had been wanting: a child.

I agree with the other poster who said a lot of times women keep quiet knowing the man will eventually come back to them. I think she thought the best way to keep their relationship on solid ground was to come home and announce her pregnancy, so that he'd forget about The Other Woman.