Most Helpful Guy
You need to say something because you don't want to be in a relationship with someone who lies to you. You need to make him understand that you can handle the truth, but lying is completely unacceptable. And you need to get on birth control if you aren't already.
Most Helpful Girl
I would ask him about it as you now know the truth and it will play on your mind otherwise. He may have faced rejection from somebody because of having 2 baby mommas or he may not not want to reveal both of them for other reasons, e. g. she messes up any relationship he has.