Second, you need to do a paternity test.
If the baby is not yours, or if the baby is yours, and your cofounder decides not to keep it, then you are a douche, but you got off lucky. Your marriage is probably destroyed, but your standing in the company might not be.
If the baby is yours, and your cofounder keeps it, and you do not take responsibility for it, expect to be booted from the company. Your marriage is probably destroyed.
If the baby is yours, and your cofounder keeps it, and you do take responsibility for it, expect to lose significant property to your wife during divorce proceedings. With lots of luck, you and your co-founder can both raise a child and maintain the company. Considering how much integrity you lack, I wouldn't count on it.